- empty column option will throw an error

papaparse.js

@@ -291,10 +291,7 @@ License: MIT
 			if (!_input.length || Array.isArray(_input[0]))
 				return serialize(null, _input, _skipEmptyLines);
 			else if (typeof _input[0] === 'object')
-				return serialize(
-					_columns ? _columns : objectKeys(_input[0]),
-					_input, _skipEmptyLines
-				);
+				return serialize(_columns || objectKeys(_input[0]), _input, _skipEmptyLines);
 		}
 		else if (typeof _input === 'object')
 		{
@@ -351,6 +348,9 @@ License: MIT
 				_writeHeader = _config.header;
 
 			if (Array.isArray(_config.columns)) {
+
+				if (_config.columns.length === 0) throw new Error('Option columns was empty');
+
 				_columns = _config.columns;
 			}
 		}

tests/test-cases.js

@@ -1742,10 +1742,10 @@ var UNPARSE_TESTS = [
 	},
 	{
 		description: "Column option is empty",
-		notes: "Header (columns) is empty so header is skipped",
+		notes: "Columns is empty so no data can be generated",
 		input: [{a: 1, b: '2'}, {}, {a: 3, d: 'd', c: 4,}],
 		config: {columns: []},
-		expected: '\r\n\r\n'
+		expectsError: true
 	}
 ];
 
@@ -1754,6 +1754,14 @@ describe('Unparse Tests', function() {
 		(test.disabled ? it.skip : it)(test.description, function() {
 			var actual;
 
+			if (test.expectsError) {
+				assert.throws(function() {
+					Papa.unparse(test.input, test.config);
+				});
+
+				return;
+			}
+
 			try {
 				actual = Papa.unparse(test.input, test.config);
 			} catch (e) {