Remove most `assert()` calls (issue 8506)

This replaces `assert` calls with `throw new FormatError()`/`throw new Error()`.
In a few places, throwing an `Error` (which is what `assert` meant) isn't correct since the enclosing function is supposed to return a `Promise`, hence some cases were changed to `Promise.reject(...)` and similarily for `createPromiseCapability` instances.

src/core/cff_parser.js

@@ -14,7 +14,7 @@
  */
 
 import {
-  assert, bytesToString, FormatError, info, isArray, stringToBytes, Util, warn
+  bytesToString, FormatError, info, isArray, stringToBytes, Util, warn
 } from '../shared/util';
 import {
   ExpertCharset, ExpertSubsetCharset, ISOAdobeCharset
@@ -871,7 +871,9 @@ var CFFParser = (function CFFParserClosure() {
         default:
           throw new FormatError(`parseFDSelect: Unknown format "${format}".`);
       }
-      assert(fdSelect.length === length, 'parseFDSelect: Invalid font data.');
+      if (fdSelect.length !== length) {
+        throw new FormatError('parseFDSelect: Invalid font data.');
+      }
 
       return new CFFFDSelect(fdSelect, rawBytes);
     },
@@ -1440,9 +1442,10 @@ var CFFCompiler = (function CFFCompilerClosure() {
                                                                   output) {
       for (var i = 0, ii = dicts.length; i < ii; ++i) {
         var fontDict = dicts[i];
-        assert(fontDict.privateDict && fontDict.hasName('Private'),
-               'There must be an private dictionary.');
         var privateDict = fontDict.privateDict;
+        if (!privateDict || !fontDict.hasName('Private')) {
+          throw new FormatError('There must be a private dictionary.');
+        }
         var privateDictTracker = new CFFOffsetTracker();
         var privateDictData = this.compileDict(privateDict, privateDictTracker);
 

src/core/chunked_stream.js

@@ -14,8 +14,8 @@
  */
 
 import {
-  arrayByteLength, arraysToBytes, assert, createPromiseCapability, isEmptyObj,
-  isInt, MissingDataException
+  arrayByteLength, arraysToBytes, createPromiseCapability, isEmptyObj, isInt,
+  MissingDataException
 } from '../shared/util';
 
 var ChunkedStream = (function ChunkedStreamClosure() {
@@ -58,12 +58,15 @@ var ChunkedStream = (function ChunkedStreamClosure() {
     onReceiveData: function ChunkedStream_onReceiveData(begin, chunk) {
       var end = begin + chunk.byteLength;
 
-      assert(begin % this.chunkSize === 0, 'Bad begin offset: ' + begin);
+      if (begin % this.chunkSize !== 0) {
+        throw new Error(`Bad begin offset: ${begin}`);
+      }
       // Using this.length is inaccurate here since this.start can be moved
       // See ChunkedStream.moveStart()
       var length = this.bytes.length;
-      assert(end % this.chunkSize === 0 || end === length,
-             'Bad end offset: ' + end);
+      if (end % this.chunkSize !== 0 && end !== length) {
+        throw new Error(`Bad end offset: ${end}`);
+      }
 
       this.bytes.set(new Uint8Array(chunk), begin);
       var chunkSize = this.chunkSize;

src/core/cmap.js

@@ -14,8 +14,8 @@
  */
 
 import {
-  assert, CMapCompressionType, FormatError, isInt, isString,
-  MissingDataException, Util, warn
+  CMapCompressionType, FormatError, isInt, isString, MissingDataException, Util,
+  warn
 } from '../shared/util';
 import { isCmd, isEOF, isName, isStream } from './primitives';
 import { Lexer } from './parser';
@@ -561,7 +561,9 @@ var BinaryCMapReader = (function BinaryCMapReaderClosure() {
         var sequence = !!(b & 0x10);
         var dataSize = b & 15;
 
-        assert(dataSize + 1 <= MAX_NUM_SIZE);
+        if (dataSize + 1 > MAX_NUM_SIZE) {
+          throw new Error('processBinaryCMap: Invalid dataSize.');
+        }
 
         var ucs2DataSize = 1;
         var subitemsCount = stream.readNumber();
@@ -943,7 +945,10 @@ var CMapFactory = (function CMapFactoryClosure() {
     if (BUILT_IN_CMAPS.indexOf(name) === -1) {
       return Promise.reject(new Error('Unknown CMap name: ' + name));
     }
-    assert(fetchBuiltInCMap, 'Built-in CMap parameters are not provided.');
+    if (!fetchBuiltInCMap) {
+      return Promise.reject(new Error(
+        'Built-in CMap parameters are not provided.'));
+    }
 
     return fetchBuiltInCMap(name).then(function (data) {
       var cMapData = data.cMapData, compressionType = data.compressionType;
@@ -955,11 +960,12 @@ var CMapFactory = (function CMapFactoryClosure() {
           return extendCMap(cMap, fetchBuiltInCMap, useCMap);
         });
       }
-      assert(compressionType === CMapCompressionType.NONE,
-        'TODO: Only BINARY/NONE CMap compression is currently supported.');
-      // Uncompressed CMap.
-      var lexer = new Lexer(new Stream(cMapData));
-      return parseCMap(cMap, lexer, fetchBuiltInCMap, null);
+      if (compressionType === CMapCompressionType.NONE) {
+        var lexer = new Lexer(new Stream(cMapData));
+        return parseCMap(cMap, lexer, fetchBuiltInCMap, null);
+      }
+      return Promise.reject(new Error(
+        'TODO: Only BINARY/NONE CMap compression is currently supported.'));
     });
   }
 

src/core/crypto.js

@@ -14,8 +14,8 @@
  */
 
 import {
-  assert, bytesToString, FormatError, isInt, PasswordException,
-  PasswordResponses, stringToBytes, utf8StringToString, warn
+  bytesToString, FormatError, isInt, PasswordException, PasswordResponses,
+  stringToBytes, utf8StringToString, warn
 } from '../shared/util';
 import { isDict, isName, Name } from './primitives';
 import { DecryptStream } from './stream';
@@ -1997,7 +1997,9 @@ var CipherTransformFactory = (function CipherTransformFactoryClosure() {
   }
 
   function buildCipherConstructor(cf, name, num, gen, key) {
-    assert(isName(name), 'Invalid crypt filter name.');
+    if (!isName(name)) {
+      throw new FormatError('Invalid crypt filter name.');
+    }
     var cryptFilter = cf.get(name.name);
     var cfm;
     if (cryptFilter !== null && cryptFilter !== undefined) {

src/core/document.js

@@ -13,13 +13,12 @@
  * limitations under the License.
  */
 
-import {
-  assert, info, isArray, isArrayBuffer, isNum, isSpace, isString,
-  MissingDataException, OPS, shadow, stringToBytes, stringToPDFString, Util,
-  warn
-} from '../shared/util';
 import { Catalog, ObjectLoader, XRef } from './obj';
 import { Dict, isDict, isName, isStream } from './primitives';
+import {
+  info, isArray, isArrayBuffer, isNum, isSpace, isString, MissingDataException,
+  OPS, shadow, stringToBytes, stringToPDFString, Util, warn
+} from '../shared/util';
 import { NullStream, Stream, StreamsSequenceStream } from './stream';
 import { OperatorList, PartialEvaluator } from './evaluator';
 import { AnnotationFactory } from './annotation';
@@ -355,7 +354,9 @@ var PDFDocument = (function PDFDocumentClosure() {
     } else {
       throw new Error('PDFDocument: Unknown argument type');
     }
-    assert(stream.length > 0, 'stream must have data');
+    if (stream.length <= 0) {
+      throw new Error('PDFDocument: stream must have data');
+    }
 
     this.pdfManager = pdfManager;
     this.stream = stream;

src/core/evaluator.js

@@ -673,7 +673,9 @@ var PartialEvaluator = (function PartialEvaluatorClosure() {
 
       var fontRef, xref = this.xref;
       if (font) { // Loading by ref.
-        assert(isRef(font));
+        if (!isRef(font)) {
+          throw new Error('The "font" object should be a reference.');
+        }
         fontRef = font;
       } else { // Loading by name.
         var fontRes = resources.get('Font');
@@ -866,7 +868,9 @@ var PartialEvaluator = (function PartialEvaluatorClosure() {
       resources = resources || Dict.empty;
       initialState = initialState || new EvalState();
 
-      assert(operatorList, 'getOperatorList: missing "operatorList" parameter');
+      if (!operatorList) {
+        throw new Error('getOperatorList: missing "operatorList" parameter');
+      }
 
       var self = this;
       var xref = this.xref;
@@ -928,10 +932,14 @@ var PartialEvaluator = (function PartialEvaluatorClosure() {
 
               var xobj = xobjs.get(name);
               if (xobj) {
-                assert(isStream(xobj), 'XObject should be a stream');
+                if (!isStream(xobj)) {
+                  throw new FormatError('XObject should be a stream');
+                }
 
                 var type = xobj.dict.get('Subtype');
-                assert(isName(type), 'XObject should have a Name subtype');
+                if (!isName(type)) {
+                  throw new FormatError('XObject should have a Name subtype');
+                }
 
                 if (type.name === 'Form') {
                   stateManager.save();
@@ -1087,10 +1095,14 @@ var PartialEvaluator = (function PartialEvaluatorClosure() {
 
             case OPS.shadingFill:
               var shadingRes = resources.get('Shading');
-              assert(shadingRes, 'No shading resource found');
+              if (!shadingRes) {
+                throw new FormatError('No shading resource found');
+              }
 
               var shading = shadingRes.get(args[0].name);
-              assert(shading, 'No shading object found');
+              if (!shading) {
+                throw new FormatError('No shading object found');
+              }
 
               var shadingFill = Pattern.parseShading(shading, null, xref,
                 resources, self.handler);
@@ -1636,10 +1648,14 @@ var PartialEvaluator = (function PartialEvaluatorClosure() {
               if (!xobj) {
                 break;
               }
-              assert(isStream(xobj), 'XObject should be a stream');
+              if (!isStream(xobj)) {
+                throw new FormatError('XObject should be a stream');
+              }
 
               var type = xobj.dict.get('Subtype');
-              assert(isName(type), 'XObject should have a Name subtype');
+              if (!isName(type)) {
+                throw new FormatError('XObject should have a Name subtype');
+              }
 
               if (type.name !== 'Form') {
                 skipEmptyXObjs[name] = true;
@@ -1977,7 +1993,9 @@ var PartialEvaluator = (function PartialEvaluatorClosure() {
           var cMap = properties.cMap;
           toUnicode = [];
           cMap.forEach(function(charcode, cid) {
-            assert(cid <= 0xffff, 'Max size of CID is 65,535');
+            if (cid > 0xffff) {
+              throw new FormatError('Max size of CID is 65,535');
+            }
             // e) Map the CID obtained in step (a) according to the CMap
             // obtained in step (d), producing a Unicode value.
             var ucs2 = ucs2CMap.lookup(cid);
@@ -2229,7 +2247,9 @@ var PartialEvaluator = (function PartialEvaluatorClosure() {
     preEvaluateFont: function PartialEvaluator_preEvaluateFont(dict) {
       var baseDict = dict;
       var type = dict.get('Subtype');
-      assert(isName(type), 'invalid font Subtype');
+      if (!isName(type)) {
+        throw new FormatError('invalid font Subtype');
+      }
 
       var composite = false;
       var uint8array;
@@ -2239,11 +2259,15 @@ var PartialEvaluator = (function PartialEvaluatorClosure() {
         //  - set the type according to the descendant font
         //  - get the FontDescriptor from the descendant font
         var df = dict.get('DescendantFonts');
-        assert(df, 'Descendant fonts are not specified');
+        if (!df) {
+          throw new FormatError('Descendant fonts are not specified');
+        }
         dict = (isArray(df) ? this.xref.fetchIfRef(df[0]) : df);
 
         type = dict.get('Subtype');
-        assert(isName(type), 'invalid font Subtype');
+        if (!isName(type)) {
+          throw new FormatError('invalid font Subtype');
+        }
         composite = true;
       }
 
@@ -2331,7 +2355,9 @@ var PartialEvaluator = (function PartialEvaluatorClosure() {
           // FontDescriptor was not required.
           // This case is here for compatibility.
           var baseFontName = dict.get('BaseFont');
-          assert(isName(baseFontName), 'Base font is not specified');
+          if (!isName(baseFontName)) {
+            throw new FormatError('Base font is not specified');
+          }
 
           // Using base font name as a font name.
           baseFontName = baseFontName.name.replace(/[,_]/g, '-');
@@ -2398,7 +2424,9 @@ var PartialEvaluator = (function PartialEvaluatorClosure() {
       }
       fontName = (fontName || baseFont);
 
-      assert(isName(fontName), 'invalid font name');
+      if (!isName(fontName)) {
+        throw new FormatError('invalid font name');
+      }
 
       var fontFile = descriptor.get('FontFile', 'FontFile2', 'FontFile3');
       if (fontFile) {
@@ -2494,7 +2522,9 @@ var TranslatedFont = (function TranslatedFontClosure() {
       this.sent = true;
     },
     loadType3Data(evaluator, resources, parentOperatorList, task) {
-      assert(this.font.isType3Font);
+      if (!this.font.isType3Font) {
+        throw new Error('Must be a Type3 font.');
+      }
 
       if (this.type3Loaded) {
         return this.type3Loaded;
@@ -2997,7 +3027,9 @@ var EvaluatorPreprocessor = (function EvaluatorPreprocessorClosure() {
             args = [];
           }
           args.push(obj);
-          assert(args.length <= 33, 'Too many arguments');
+          if (args.length > 33) {
+            throw new FormatError('Too many arguments');
+          }
         }
       }
     },

src/core/fonts.js

@@ -14,9 +14,9 @@
  */
 
 import {
-  assert, bytesToString, FONT_IDENTITY_MATRIX, FontType, FormatError, info,
-  isArray, isInt, isNum, isSpace, MissingDataException, readUint32, shadow,
-  string32, warn
+  bytesToString, FONT_IDENTITY_MATRIX, FontType, FormatError, info, isArray,
+  isInt, isNum, isSpace, MissingDataException, readUint32, shadow, string32,
+  warn
 } from '../shared/util';
 import {
   CFF, CFFCharset, CFFCompiler, CFFHeader, CFFIndex, CFFParser, CFFPrivateDict,
@@ -2286,7 +2286,9 @@ var Font = (function FontClosure() {
         var isCidToGidMapEmpty = cidToGidMap.length === 0;
 
         properties.cMap.forEach(function(charCode, cid) {
-          assert(cid <= 0xffff, 'Max size of CID is 65,535');
+          if (cid > 0xffff) {
+            throw new FormatError('Max size of CID is 65,535');
+          }
           var glyphId = -1;
           if (isCidToGidMapEmpty) {
             glyphId = cid;

src/core/obj.js

@@ -14,8 +14,8 @@
  */
 
 import {
-  assert, bytesToString, createPromiseCapability, createValidAbsoluteUrl,
-  FormatError, info, InvalidPDFException, isArray, isBool, isInt, isString,
+  bytesToString, createPromiseCapability, createValidAbsoluteUrl, FormatError,
+  info, InvalidPDFException, isArray, isBool, isInt, isString,
   MissingDataException, shadow, stringToPDFString, stringToUTF8String, Util,
   warn, XRefParseException
 } from '../shared/util';
@@ -33,7 +33,9 @@ var Catalog = (function CatalogClosure() {
     this.pdfManager = pdfManager;
     this.xref = xref;
     this.catDict = xref.getCatalogObj();
-    assert(isDict(this.catDict), 'catalog object is not a dictionary');
+    if (!isDict(this.catDict)) {
+      throw new FormatError('catalog object is not a dictionary');
+    }
 
     this.fontCache = new RefSetCache();
     this.builtInCMapCache = Object.create(null);
@@ -80,7 +82,9 @@ var Catalog = (function CatalogClosure() {
     },
     get toplevelPagesDict() {
       var pagesObj = this.catDict.get('Pages');
-      assert(isDict(pagesObj), 'invalid top-level pages dictionary');
+      if (!isDict(pagesObj)) {
+        throw new FormatError('invalid top-level pages dictionary');
+      }
       // shadow the prototype getter
       return shadow(this, 'toplevelPagesDict', pagesObj);
     },
@@ -118,7 +122,9 @@ var Catalog = (function CatalogClosure() {
         if (outlineDict === null) {
           continue;
         }
-        assert(outlineDict.has('Title'), 'Invalid outline item');
+        if (!outlineDict.has('Title')) {
+          throw new FormatError('Invalid outline item');
+        }
 
         var data = { url: null, dest: null, };
         Catalog.parseDestDictionary({
@@ -163,10 +169,10 @@ var Catalog = (function CatalogClosure() {
     },
     get numPages() {
       var obj = this.toplevelPagesDict.get('Count');
-      assert(
-        isInt(obj),
-        'page count in top level pages object is not an integer'
-      );
+      if (!isInt(obj)) {
+        throw new FormatError(
+          'page count in top level pages object is not an integer');
+      }
       // shadow the prototype getter
       return shadow(this, 'numPages', obj);
     },
@@ -258,23 +264,31 @@ var Catalog = (function CatalogClosure() {
       for (var i = 0, ii = this.numPages; i < ii; i++) {
         if (i in nums) {
           var labelDict = nums[i];
-          assert(isDict(labelDict), 'The PageLabel is not a dictionary.');
+          if (!isDict(labelDict)) {
+            throw new FormatError('The PageLabel is not a dictionary.');
+          }
 
           var type = labelDict.get('Type');
-          assert(!type || isName(type, 'PageLabel'),
-                 'Invalid type in PageLabel dictionary.');
+          if (type && !isName(type, 'PageLabel')) {
+            throw new FormatError('Invalid type in PageLabel dictionary.');
+          }
 
           var s = labelDict.get('S');
-          assert(!s || isName(s), 'Invalid style in PageLabel dictionary.');
+          if (s && !isName(s)) {
+            throw new FormatError('Invalid style in PageLabel dictionary.');
+          }
           style = s ? s.name : null;
 
           var p = labelDict.get('P');
-          assert(!p || isString(p), 'Invalid prefix in PageLabel dictionary.');
+          if (p && !isString(p)) {
+            throw new FormatError('Invalid prefix in PageLabel dictionary.');
+          }
           prefix = p ? stringToPDFString(p) : '';
 
           var st = labelDict.get('St');
-          assert(!st || (isInt(st) && st >= 1),
-                 'Invalid start in PageLabel dictionary.');
+          if (st && !(isInt(st) && st >= 1)) {
+            throw new FormatError('Invalid start in PageLabel dictionary.');
+          }
           currentIndex = st || 1;
         }
 
@@ -302,8 +316,10 @@ var Catalog = (function CatalogClosure() {
             currentLabel = charBuf.join('');
             break;
           default:
-            assert(!style,
-                   'Invalid style "' + style + '" in PageLabel dictionary.');
+            if (style) {
+              throw new FormatError(
+                `Invalid style "${style}" in PageLabel dictionary.`);
+            }
         }
         pageLabels[i] = prefix + currentLabel;
 
@@ -454,8 +470,11 @@ var Catalog = (function CatalogClosure() {
           }
 
           // Must be a child page dictionary.
-          assert(isDict(currentNode),
-            'page dictionary kid reference points to wrong type of object');
+          if (!isDict(currentNode)) {
+            capability.reject(new FormatError(
+              'page dictionary kid reference points to wrong type of object'));
+            return;
+          }
 
           count = currentNode.get('Count');
           // Cache the Kids count, since it can reduce redundant lookups in long
@@ -471,7 +490,11 @@ var Catalog = (function CatalogClosure() {
           }
 
           var kids = currentNode.get('Kids');
-          assert(isArray(kids), 'page dictionary kids object is not an array');
+          if (!isArray(kids)) {
+            capability.reject(new FormatError(
+              'page dictionary kids object is not an array'));
+            return;
+          }
 
           // Always check all `Kids` nodes, to avoid getting stuck in an empty
           // node further down in the tree (see issue5644.pdf, issue8088.pdf),
@@ -480,7 +503,7 @@ var Catalog = (function CatalogClosure() {
             nodesToVisit.push(kids[last]);
           }
         }
-        capability.reject('Page index ' + pageIndex + ' not found.');
+        capability.reject(new Error('Page index ' + pageIndex + ' not found.'));
       }
       next();
       return capability.promise;
@@ -497,19 +520,24 @@ var Catalog = (function CatalogClosure() {
         return xref.fetchAsync(kidRef).then(function (node) {
           if (isRefsEqual(kidRef, pageRef) && !isDict(node, 'Page') &&
               !(isDict(node) && !node.has('Type') && node.has('Contents'))) {
-            throw new Error('The reference does not point to a /Page Dict.');
+            throw new FormatError(
+              'The reference does not point to a /Page Dict.');
           }
           if (!node) {
             return null;
           }
-          assert(isDict(node), 'node must be a Dict.');
+          if (!isDict(node)) {
+            throw new FormatError('node must be a Dict.');
+          }
           parentRef = node.getRaw('Parent');
           return node.getAsync('Parent');
         }).then(function (parent) {
           if (!parent) {
             return null;
           }
-          assert(isDict(parent), 'parent must be a Dict.');
+          if (!isDict(parent)) {
+            throw new FormatError('parent must be a Dict.');
+          }
           return parent.getAsync('Kids');
         }).then(function (kids) {
           if (!kids) {
@@ -519,7 +547,9 @@ var Catalog = (function CatalogClosure() {
           var found = false;
           for (var i = 0; i < kids.length; i++) {
             var kid = kids[i];
-            assert(isRef(kid), 'kid must be a Ref.');
+            if (!isRef(kid)) {
+              throw new FormatError('kid must be a Ref.');
+            }
             if (kid.num === kidRef.num) {
               found = true;
               break;
@@ -1229,7 +1259,9 @@ var XRef = (function XRefClosure() {
     },
 
     fetch: function XRef_fetch(ref, suppressEncryption) {
-      assert(isRef(ref), 'ref object is not a reference');
+      if (!isRef(ref)) {
+        throw new Error('ref object is not a reference');
+      }
       var num = ref.num;
       if (num in this.cache) {
         var cacheEntry = this.cache[num];
@@ -1415,8 +1447,9 @@ var NameOrNumberTree = (function NameOrNumberTreeClosure() {
           var kids = obj.get('Kids');
           for (i = 0, n = kids.length; i < n; i++) {
             var kid = kids[i];
-            assert(!processed.has(kid),
-                   'Duplicate entry in "' + this._type + '" tree.');
+            if (processed.has(kid)) {
+              throw new FormatError(`Duplicate entry in "${this._type}" tree.`);
+            }
             queue.push(kid);
             processed.put(kid);
           }

src/core/pattern.js

@@ -328,7 +328,9 @@ Shadings.Mesh = (function MeshClosure() {
       var coord = reader.readCoordinate();
       var color = reader.readComponents();
       if (verticesLeft === 0) { // ignoring flags if we started a triangle
-        assert((0 <= f && f <= 2), 'Unknown type4 flag');
+        if (!(0 <= f && f <= 2)) {
+          throw new FormatError('Unknown type4 flag');
+        }
         switch (f) {
           case 0:
             verticesLeft = 3;
@@ -492,7 +494,9 @@ Shadings.Mesh = (function MeshClosure() {
     var cs = new Int32Array(4); // c00, c30, c03, c33
     while (reader.hasData) {
       var f = reader.readFlag();
-      assert((0 <= f && f <= 3), 'Unknown type6 flag');
+      if (!(0 <= f && f <= 3)) {
+        throw new FormatError('Unknown type6 flag');
+      }
       var i, ii;
       var pi = coords.length;
       for (i = 0, ii = (f !== 0 ? 8 : 12); i < ii; i++) {
@@ -602,7 +606,9 @@ Shadings.Mesh = (function MeshClosure() {
     var cs = new Int32Array(4); // c00, c30, c03, c33
     while (reader.hasData) {
       var f = reader.readFlag();
-      assert((0 <= f && f <= 3), 'Unknown type7 flag');
+      if (!(0 <= f && f <= 3)) {
+        throw new FormatError('Unknown type7 flag');
+      }
       var i, ii;
       var pi = coords.length;
       for (i = 0, ii = (f !== 0 ? 12 : 16); i < ii; i++) {
@@ -706,7 +712,9 @@ Shadings.Mesh = (function MeshClosure() {
   }
 
   function Mesh(stream, matrix, xref, res) {
-    assert(isStream(stream), 'Mesh data is not a stream');
+    if (!isStream(stream)) {
+      throw new FormatError('Mesh data is not a stream');
+    }
     var dict = stream.dict;
     this.matrix = matrix;
     this.shadingType = dict.get('ShadingType');
@@ -743,7 +751,9 @@ Shadings.Mesh = (function MeshClosure() {
         break;
       case ShadingType.LATTICE_FORM_MESH:
         var verticesPerRow = dict.get('VerticesPerRow') | 0;
-        assert(verticesPerRow >= 2, 'Invalid VerticesPerRow');
+        if (verticesPerRow < 2) {
+          throw new FormatError('Invalid VerticesPerRow');
+        }
         decodeType5Shading(this, reader, verticesPerRow);
         break;
       case ShadingType.COONS_PATCH_MESH:

src/core/worker.js

@@ -541,7 +541,9 @@ var WorkerMessageHandler = {
         if (source.chunkedViewerLoading) {
           pdfStream = new PDFWorkerStream(source, handler);
         } else {
-          assert(PDFNetworkStream, './network module is not loaded');
+          if (!PDFNetworkStream) {
+            throw new Error('./network module is not loaded');
+          }
           pdfStream = new PDFNetworkStream(data);
         }
       } catch (ex) {

src/display/canvas.js

@@ -14,7 +14,7 @@
  */
 
 import {
-  assert, FONT_IDENTITY_MATRIX, IDENTITY_MATRIX, ImageKind, info, isArray,
+  FONT_IDENTITY_MATRIX, IDENTITY_MATRIX, ImageKind, info, isArray,
   isLittleEndian, isNum, OPS, shadow, TextRenderingMode, Util, warn
 } from '../shared/util';
 import { getShadingPatternFromIR, TilingPattern } from './pattern_helper';
@@ -1777,7 +1777,9 @@ var CanvasGraphics = (function CanvasGraphicsClosure() {
       if (group.matrix) {
         currentCtx.transform.apply(currentCtx, group.matrix);
       }
-      assert(group.bbox, 'Bounding box is required.');
+      if (!group.bbox) {
+        throw new Error('Bounding box is required.');
+      }
 
       // Based on the current transform figure out how big the bounding box
       // will actually be.

src/display/dom_utils.js

@@ -14,7 +14,7 @@
  */
 
 import {
-  assert, CMapCompressionType, createValidAbsoluteUrl, deprecated, globalScope,
+  CMapCompressionType, createValidAbsoluteUrl, deprecated, globalScope,
   removeNullCharacters, stringToBytes, warn
 } from '../shared/util';
 
@@ -22,7 +22,9 @@ var DEFAULT_LINK_REL = 'noopener noreferrer nofollow';
 
 class DOMCanvasFactory {
   create(width, height) {
-    assert(width > 0 && height > 0, 'invalid canvas size');
+    if (width <= 0 || height <= 0) {
+      throw new Error('invalid canvas size');
+    }
     let canvas = document.createElement('canvas');
     let context = canvas.getContext('2d');
     canvas.width = width;
@@ -34,14 +36,20 @@ class DOMCanvasFactory {
   }
 
   reset(canvasAndContext, width, height) {
-    assert(canvasAndContext.canvas, 'canvas is not specified');
-    assert(width > 0 && height > 0, 'invalid canvas size');
+    if (!canvasAndContext.canvas) {
+      throw new Error('canvas is not specified');
+    }
+    if (width <= 0 || height <= 0) {
+      throw new Error('invalid canvas size');
+    }
     canvasAndContext.canvas.width = width;
     canvasAndContext.canvas.height = height;
   }
 
   destroy(canvasAndContext) {
-    assert(canvasAndContext.canvas, 'canvas is not specified');
+    if (!canvasAndContext.canvas) {
+      throw new Error('canvas is not specified');
+    }
     // Zeroing the width and height cause Firefox to release graphics
     // resources immediately, which can greatly reduce memory consumption.
     canvasAndContext.canvas.width = 0;