Error is a constructor, ‘new’ is not required.

demos/blockfactory/block_definition_extractor.js

@@ -476,7 +476,7 @@ BlockDefinitionExtractor.buildFieldDropdown_ = function(dropdown) {
   } else if (Array.isArray(menuGenerator)) {
     var options = menuGenerator;
   } else {
-    throw new Error('Unrecognized type of menuGenerator: ' + menuGenerator);
+    throw Error('Unrecognized type of menuGenerator: ' + menuGenerator);
   }
 
   var fieldDropdown = BlockDefinitionExtractor.newDomElement_(

demos/blockfactory/factory_utils.js

@@ -767,7 +767,7 @@ FactoryUtils.getBlockTypeFromJsDefinition = function(blockDef) {
   if (indexOfStartBracket != -1 && indexOfEndBracket != -1) {
     return blockDef.substring(indexOfStartBracket + 2, indexOfEndBracket);
   } else {
-    throw new Error ('Could not parse block type out of JavaScript block ' +
+    throw Error('Could not parse block type out of JavaScript block ' +
         'definition. Brackets normally enclosing block type not found.');
   }
 };
@@ -921,7 +921,7 @@ FactoryUtils.sameBlockXml = function(blockXml1, blockXml2) {
   // Each XML element should contain a single child element with a 'block' tag
   if (blockXml1.tagName.toLowerCase() != 'xml' ||
       blockXml2.tagName.toLowerCase() != 'xml') {
-    throw new Error('Expected two XML elements, received elements with tag ' +
+    throw Error('Expected two XML elements, received elements with tag ' +
         'names: ' + blockXml1.tagName + ' and ' + blockXml2.tagName + '.');
   }
 
@@ -931,7 +931,7 @@ FactoryUtils.sameBlockXml = function(blockXml1, blockXml2) {
   var blockElement2 = blockXml2.getElementsByTagName('block')[0];
 
   if (!(blockElement1 && blockElement2)) {
-    throw new Error('Could not get find block element in XML.');
+    throw Error('Could not get find block element in XML.');
   }
 
   var cleanBlockXml1 = FactoryUtils.cleanXml(blockElement1);

demos/blockfactory/workspacefactory/wfactory_controller.js

@@ -340,7 +340,7 @@ WorkspaceFactoryController.prototype.exportXmlFile = function(exportMode) {
     // Unknown mode. Throw error.
     var msg = 'Unknown export mode: ' + exportMode;
     BlocklyDevTools.Analytics.onError(msg);
-    throw new Error(msg);
+    throw Error(msg);
   }
 
   // Unpack self-closing tags.  These tags fail when embedded in HTML.
@@ -760,7 +760,7 @@ WorkspaceFactoryController.prototype.importFile = function(file, importMode) {
         BlocklyDevTools.Analytics.onImport('WorkspaceContents.xml');
       } else {
         // Throw error if invalid mode.
-        throw new Error('Unknown import mode: ' + importMode);
+        throw Error('Unknown import mode: ' + importMode);
       }
     } catch(e) {
       var msg = 'Cannot load XML from file.';

demos/blockfactory/workspacefactory/wfactory_generator.js

@@ -71,7 +71,7 @@ WorkspaceFactoryGenerator.prototype.generateToolboxXml = function() {
     // Toolbox has categories.
     // Assert that selected != null
     if (!this.model.getSelected()) {
-      throw new Error('Selected is null when the toolbox is empty.');
+      throw Error('Selected is null when the toolbox is empty.');
     }
 
     var xml = this.model.getSelectedXml();

demos/blockfactory/workspacefactory/wfactory_model.js

@@ -164,7 +164,7 @@ WorkspaceFactoryModel.prototype.moveElementToIndex = function(element, newIndex,
   // Check that indexes are in bounds.
   if (newIndex < 0 || newIndex >= this.toolboxList.length || oldIndex < 0 ||
       oldIndex >= this.toolboxList.length) {
-    throw new Error('Index out of bounds when moving element in the model.');
+    throw Error('Index out of bounds when moving element in the model.');
   }
   this.deleteElementFromList(oldIndex);
   this.toolboxList.splice(newIndex, 0, element);

demos/blockfactory/workspacefactory/wfactory_view.js

@@ -201,7 +201,7 @@ WorkspaceFactoryView.prototype.moveTabToIndex =
   // Check that indexes are in bounds.
   if (newIndex < 0 || newIndex >= table.rows.length || oldIndex < 0 ||
       oldIndex >= table.rows.length) {
-    throw new Error('Index out of bounds when moving tab in the view.');
+    throw Error('Index out of bounds when moving tab in the view.');
   }
 
   if (newIndex < oldIndex) {