Strict null check work in extHost and mainThread language Features

- annotate undefined returned types
- Don't call functions with null or undefined values.
- Refactor _convertCompletionItem so that we don't need to mutate the returned object
- Suppress a type error related to electricCharacters.

src/tsconfig.strictNullChecks.json

@@ -63,6 +63,7 @@
 		"./vs/workbench/api/electron-browser/mainThreadFileSystem.ts",
 		"./vs/workbench/api/electron-browser/mainThreadFileSystemEventService.ts",
 		"./vs/workbench/api/electron-browser/mainThreadHeapService.ts",
+		"./vs/workbench/api/electron-browser/mainThreadLanguageFeatures.ts",
 		"./vs/workbench/api/electron-browser/mainThreadLanguages.ts",
 		"./vs/workbench/api/electron-browser/mainThreadLogService.ts",
 		"./vs/workbench/api/electron-browser/mainThreadMessageService.ts",

src/vs/editor/common/modes/languageConfiguration.ts

@@ -170,7 +170,7 @@ export interface IDocComment {
 	/**
 	 * The string that appears on the last line and closes the doc comment (e.g. ' * /').
 	 */
-	close: string;
+	close?: string;
 }
 
 /**

src/vs/editor/common/modes/supports/electricCharacter.ts

@@ -33,7 +33,7 @@ export class BracketElectricCharacterSupport {
 		this._complexAutoClosePairs = autoClosePairs.filter(pair => pair.open.length > 1 && !!pair.close).map(el => new StandardAutoClosingPairConditional(el));
 		if (contribution.docComment) {
 			// IDocComment is legacy, only partially supported
-			this._complexAutoClosePairs.push(new StandardAutoClosingPairConditional({ open: contribution.docComment.open, close: contribution.docComment.close }));
+			this._complexAutoClosePairs.push(new StandardAutoClosingPairConditional({ open: contribution.docComment.open, close: contribution.docComment.close || '' }));
 		}
 	}
 

src/vs/monaco.d.ts

@@ -4592,7 +4592,7 @@ declare namespace monaco.languages {
 		/**
 		 * The string that appears on the last line and closes the doc comment (e.g. ' * /').
 		 */
-		close: string;
+		close?: string;
 	}
 
 	/**

src/vs/workbench/api/electron-browser/mainThreadLanguageFeatures.ts

@@ -137,17 +137,21 @@ export class MainThreadLanguageFeatures implements MainThreadLanguageFeaturesSha
 					if (dto) {
 						dto.forEach(obj => {
 							this._heapService.trackObject(obj);
-							this._heapService.trackObject(obj.command);
+							if (obj.command) {
+								this._heapService.trackObject(obj.command);
+							}
 						});
 					}
 					return dto;
 				});
 			},
-			resolveCodeLens: (model: ITextModel, codeLens: modes.ICodeLensSymbol, token: CancellationToken): modes.ICodeLensSymbol | Promise<modes.ICodeLensSymbol> => {
+			resolveCodeLens: (model: ITextModel, codeLens: modes.ICodeLensSymbol, token: CancellationToken): Promise<modes.ICodeLensSymbol | undefined> => {
 				return this._proxy.$resolveCodeLens(handle, model.uri, codeLens, token).then(obj => {
 					if (obj) {
 						this._heapService.trackObject(obj);
-						this._heapService.trackObject(obj.command);
+						if (obj.command) {
+							this._heapService.trackObject(obj.command);
+						}
 					}
 					return obj;
 				});
@@ -269,7 +273,13 @@ export class MainThreadLanguageFeatures implements MainThreadLanguageFeaturesSha
 		this._registrations[handle] = modes.CodeActionProviderRegistry.register(typeConverters.LanguageSelector.from(selector), <modes.CodeActionProvider>{
 			provideCodeActions: (model: ITextModel, rangeOrSelection: EditorRange | Selection, context: modes.CodeActionContext, token: CancellationToken): Promise<modes.CodeAction[]> => {
 				return this._proxy.$provideCodeActions(handle, model.uri, rangeOrSelection, context, token).then(dto => {
-					if (dto) { dto.forEach(obj => this._heapService.trackObject(obj.command)); }
+					if (dto) {
+						dto.forEach(obj => {
+							if (obj.command) {
+								this._heapService.trackObject(obj.command);
+							}
+						});
+					}
 					return MainThreadLanguageFeatures._reviveCodeActionDto(dto);
 				});
 			},
@@ -321,8 +331,13 @@ export class MainThreadLanguageFeatures implements MainThreadLanguageFeaturesSha
 					return MainThreadLanguageFeatures._reviveWorkspaceSymbolDto(result.symbols);
 				});
 			},
-			resolveWorkspaceSymbol: (item: search.IWorkspaceSymbol, token: CancellationToken): Promise<search.IWorkspaceSymbol> => {
-				return this._proxy.$resolveWorkspaceSymbol(handle, item, token).then(i => MainThreadLanguageFeatures._reviveWorkspaceSymbolDto(i));
+			resolveWorkspaceSymbol: (item: search.IWorkspaceSymbol, token: CancellationToken): Promise<search.IWorkspaceSymbol | undefined> => {
+				return this._proxy.$resolveWorkspaceSymbol(handle, item, token).then(i => {
+					if (i) {
+						return MainThreadLanguageFeatures._reviveWorkspaceSymbolDto(i);
+					}
+					return undefined;
+				});
 			}
 		});
 	}
@@ -346,7 +361,7 @@ export class MainThreadLanguageFeatures implements MainThreadLanguageFeaturesSha
 	$registerSuggestSupport(handle: number, selector: ISerializedDocumentFilter[], triggerCharacters: string[], supportsResolveDetails: boolean): void {
 		this._registrations[handle] = modes.CompletionProviderRegistry.register(typeConverters.LanguageSelector.from(selector), <modes.CompletionItemProvider>{
 			triggerCharacters,
-			provideCompletionItems: (model: ITextModel, position: EditorPosition, context: modes.CompletionContext, token: CancellationToken): Promise<modes.CompletionList> => {
+			provideCompletionItems: (model: ITextModel, position: EditorPosition, context: modes.CompletionContext, token: CancellationToken): Promise<modes.CompletionList | undefined> => {
 				return this._proxy.$provideCompletionItems(handle, model.uri, position, context, token).then(result => {
 					if (!result) {
 						return result;
@@ -354,7 +369,11 @@ export class MainThreadLanguageFeatures implements MainThreadLanguageFeaturesSha
 					return {
 						suggestions: result.suggestions,
 						incomplete: result.incomplete,
-						dispose: () => this._proxy.$releaseCompletionItems(handle, result._id)
+						dispose: () => {
+							if (typeof result._id === 'number') {
+								this._proxy.$releaseCompletionItems(handle, result._id);
+							}
+						}
 					};
 				});
 			},
@@ -372,7 +391,7 @@ export class MainThreadLanguageFeatures implements MainThreadLanguageFeaturesSha
 			signatureHelpTriggerCharacters: metadata.triggerCharacters,
 			signatureHelpRetriggerCharacters: metadata.retriggerCharacters,
 
-			provideSignatureHelp: (model: ITextModel, position: EditorPosition, token: CancellationToken, context: modes.SignatureHelpContext): Promise<modes.SignatureHelp> => {
+			provideSignatureHelp: (model: ITextModel, position: EditorPosition, token: CancellationToken, context: modes.SignatureHelpContext): Promise<modes.SignatureHelp | undefined> => {
 				return this._proxy.$provideSignatureHelp(handle, model.uri, position, context, token);
 			}
 		});
@@ -395,8 +414,10 @@ export class MainThreadLanguageFeatures implements MainThreadLanguageFeaturesSha
 			},
 			resolveLink: (link, token) => {
 				return this._proxy.$resolveDocumentLink(handle, link, token).then(obj => {
-					MainThreadLanguageFeatures._reviveLinkDTO(obj);
-					this._heapService.trackObject(obj);
+					if (obj) {
+						MainThreadLanguageFeatures._reviveLinkDTO(obj);
+						this._heapService.trackObject(obj);
+					}
 					return obj;
 				});
 			}
@@ -461,46 +482,28 @@ export class MainThreadLanguageFeatures implements MainThreadLanguageFeaturesSha
 	// --- configuration
 
 	private static _reviveRegExp(regExp: ISerializedRegExp): RegExp {
-		if (typeof regExp === 'undefined') {
-			return undefined;
-		}
-		if (regExp === null) {
-			return null;
-		}
 		return new RegExp(regExp.pattern, regExp.flags);
 	}
 
 	private static _reviveIndentationRule(indentationRule: ISerializedIndentationRule): IndentationRule {
-		if (typeof indentationRule === 'undefined') {
-			return undefined;
-		}
-		if (indentationRule === null) {
-			return null;
-		}
 		return {
 			decreaseIndentPattern: MainThreadLanguageFeatures._reviveRegExp(indentationRule.decreaseIndentPattern),
 			increaseIndentPattern: MainThreadLanguageFeatures._reviveRegExp(indentationRule.increaseIndentPattern),
-			indentNextLinePattern: MainThreadLanguageFeatures._reviveRegExp(indentationRule.indentNextLinePattern),
-			unIndentedLinePattern: MainThreadLanguageFeatures._reviveRegExp(indentationRule.unIndentedLinePattern),
+			indentNextLinePattern: indentationRule.indentNextLinePattern ? MainThreadLanguageFeatures._reviveRegExp(indentationRule.indentNextLinePattern) : undefined,
+			unIndentedLinePattern: indentationRule.unIndentedLinePattern ? MainThreadLanguageFeatures._reviveRegExp(indentationRule.unIndentedLinePattern) : undefined,
 		};
 	}
 
 	private static _reviveOnEnterRule(onEnterRule: ISerializedOnEnterRule): OnEnterRule {
 		return {
 			beforeText: MainThreadLanguageFeatures._reviveRegExp(onEnterRule.beforeText),
-			afterText: MainThreadLanguageFeatures._reviveRegExp(onEnterRule.afterText),
-			oneLineAboveText: MainThreadLanguageFeatures._reviveRegExp(onEnterRule.oneLineAboveText),
+			afterText: onEnterRule.afterText ? MainThreadLanguageFeatures._reviveRegExp(onEnterRule.afterText) : undefined,
+			oneLineAboveText: onEnterRule.oneLineAboveText ? MainThreadLanguageFeatures._reviveRegExp(onEnterRule.oneLineAboveText) : undefined,
 			action: onEnterRule.action
 		};
 	}
 
 	private static _reviveOnEnterRules(onEnterRules: ISerializedOnEnterRule[]): OnEnterRule[] {
-		if (typeof onEnterRules === 'undefined') {
-			return undefined;
-		}
-		if (onEnterRules === null) {
-			return null;
-		}
 		return onEnterRules.map(MainThreadLanguageFeatures._reviveOnEnterRule);
 	}
 
@@ -509,13 +512,13 @@ export class MainThreadLanguageFeatures implements MainThreadLanguageFeaturesSha
 		const configuration: LanguageConfiguration = {
 			comments: _configuration.comments,
 			brackets: _configuration.brackets,
-			wordPattern: MainThreadLanguageFeatures._reviveRegExp(_configuration.wordPattern),
-			indentationRules: MainThreadLanguageFeatures._reviveIndentationRule(_configuration.indentationRules),
-			onEnterRules: MainThreadLanguageFeatures._reviveOnEnterRules(_configuration.onEnterRules),
+			wordPattern: _configuration.wordPattern ? MainThreadLanguageFeatures._reviveRegExp(_configuration.wordPattern) : undefined,
+			indentationRules: _configuration.indentationRules ? MainThreadLanguageFeatures._reviveIndentationRule(_configuration.indentationRules) : undefined,
+			onEnterRules: _configuration.onEnterRules ? MainThreadLanguageFeatures._reviveOnEnterRules(_configuration.onEnterRules) : undefined,
 
-			autoClosingPairs: null,
-			surroundingPairs: null,
-			__electricCharacterSupport: null
+			autoClosingPairs: undefined,
+			surroundingPairs: undefined,
+			__electricCharacterSupport: undefined
 		};
 
 		if (_configuration.__characterPairSupport) {

src/vs/workbench/api/node/extHost.protocol.ts

@@ -312,7 +312,7 @@ export interface MainThreadLanguageFeaturesShape extends IDisposable {
 	$unregister(handle: number): void;
 	$registerDocumentSymbolProvider(handle: number, selector: ISerializedDocumentFilter[], label: string): void;
 	$registerCodeLensSupport(handle: number, selector: ISerializedDocumentFilter[], eventHandle: number | undefined): void;
-	$registerCodeInsetSupport(handle: number, selector: ISerializedDocumentFilter[], eventHandle: number): void;
+	$registerCodeInsetSupport(handle: number, selector: ISerializedDocumentFilter[], eventHandle: number | undefined): void;
 	$emitCodeLensEvent(eventHandle: number, event?: any): void;
 	$registerDefinitionSupport(handle: number, selector: ISerializedDocumentFilter[]): void;
 	$registerDeclarationSupport(handle: number, selector: ISerializedDocumentFilter[]): void;
@@ -922,7 +922,7 @@ export interface ExtHostLanguageFeaturesShape {
 	$provideDocumentSymbols(handle: number, resource: UriComponents, token: CancellationToken): Promise<modes.DocumentSymbol[] | undefined>;
 	$provideCodeLenses(handle: number, resource: UriComponents, token: CancellationToken): Promise<CodeLensDto[]>;
 	$resolveCodeLens(handle: number, resource: UriComponents, symbol: CodeLensDto, token: CancellationToken): Promise<CodeLensDto | undefined>;
-	$provideCodeInsets(handle: number, resource: UriComponents, token: CancellationToken): Promise<CodeInsetDto[]>;
+	$provideCodeInsets(handle: number, resource: UriComponents, token: CancellationToken): Promise<CodeInsetDto[] | undefined>;
 	$resolveCodeInset(handle: number, resource: UriComponents, symbol: CodeInsetDto, token: CancellationToken): Promise<CodeInsetDto>;
 	$provideDefinition(handle: number, resource: UriComponents, position: IPosition, token: CancellationToken): Promise<DefinitionLinkDto[]>;
 	$provideDeclaration(handle: number, resource: UriComponents, position: IPosition, token: CancellationToken): Promise<DefinitionLinkDto[]>;
@@ -940,7 +940,7 @@ export interface ExtHostLanguageFeaturesShape {
 	$releaseWorkspaceSymbols(handle: number, id: number): void;
 	$provideRenameEdits(handle: number, resource: UriComponents, position: IPosition, newName: string, token: CancellationToken): Promise<WorkspaceEditDto | undefined>;
 	$resolveRenameLocation(handle: number, resource: UriComponents, position: IPosition, token: CancellationToken): Promise<modes.RenameLocation | undefined>;
-	$provideCompletionItems(handle: number, resource: UriComponents, position: IPosition, context: modes.CompletionContext, token: CancellationToken): Promise<SuggestResultDto>;
+	$provideCompletionItems(handle: number, resource: UriComponents, position: IPosition, context: modes.CompletionContext, token: CancellationToken): Promise<SuggestResultDto | undefined>;
 	$resolveCompletionItem(handle: number, resource: UriComponents, position: IPosition, suggestion: modes.CompletionItem, token: CancellationToken): Promise<modes.CompletionItem>;
 	$releaseCompletionItems(handle: number, id: number): void;
 	$provideSignatureHelp(handle: number, resource: UriComponents, position: IPosition, context: modes.SignatureHelpContext, token: CancellationToken): Promise<modes.SignatureHelp | undefined>;

src/vs/workbench/api/node/extHostLanguageFeatures.ts

@@ -500,7 +500,7 @@ class NavigateTypeAdapter {
 			}
 		}).then(() => {
 			if (result.symbols.length > 0) {
-				this._resultCache[result._id] = [result.symbols[0]._id, result.symbols[result.symbols.length - 1]._id];
+				this._resultCache[result._id!] = [result.symbols[0]._id!, result.symbols[result.symbols.length - 1]._id!];
 			}
 			return result;
 		});
@@ -633,12 +633,12 @@ class SuggestAdapter {
 		this._provider = provider;
 	}
 
-	provideCompletionItems(resource: URI, position: IPosition, context: modes.CompletionContext, token: CancellationToken): Promise<SuggestResultDto> {
+	provideCompletionItems(resource: URI, position: IPosition, context: modes.CompletionContext, token: CancellationToken): Promise<SuggestResultDto | undefined> {
 
 		const doc = this._documents.getDocument(resource);
 		const pos = typeConvert.Position.to(position);
 
-		return asPromise<vscode.CompletionItem[] | vscode.CompletionList>(
+		return asPromise<vscode.CompletionItem[] | vscode.CompletionList | null | undefined>(
 			() => this._provider.provideCompletionItems(doc, pos, token, typeConvert.CompletionContext.to(context))
 		).then(value => {
 
@@ -720,7 +720,14 @@ class SuggestAdapter {
 			return undefined;
 		}
 
-		const result: SuggestionDto = {
+		// 'overwrite[Before|After]'-logic
+		const range = this.getRange(item, defaultRange);
+		if (!range.isSingleLine || range.start.line !== position.line) {
+			console.warn('INVALID text edit -> must be single line and on the same line');
+			return undefined;
+		}
+
+		return {
 			//
 			_id,
 			_parentId,
@@ -733,46 +740,47 @@ class SuggestAdapter {
 			sortText: item.sortText,
 			preselect: item.preselect,
 			//
-			range: undefined,
-			insertText: undefined,
-			insertTextRules: item.keepWhitespace ? modes.CompletionItemInsertTextRule.KeepWhitespace : 0,
+			range: typeConvert.Range.from(range),
+			insertText: this.convertInsertText(item),
+			insertTextRules: this.convertInsertTextRules(item),
 			additionalTextEdits: item.additionalTextEdits && item.additionalTextEdits.map(typeConvert.TextEdit.from),
 			command: this._commands.toInternal(item.command),
 			commitCharacters: item.commitCharacters
 		};
+	}
 
+	private convertInsertText(item: vscode.CompletionItem): string {
 		// 'insertText'-logic
 		if (item.textEdit) {
-			result.insertText = item.textEdit.newText;
-
+			return item.textEdit.newText;
 		} else if (typeof item.insertText === 'string') {
-			result.insertText = item.insertText;
-
+			return item.insertText;
 		} else if (item.insertText instanceof SnippetString) {
-			result.insertText = item.insertText.value;
-			result.insertTextRules += modes.CompletionItemInsertTextRule.InsertAsSnippet;
-
+			return item.insertText.value;
 		} else {
-			result.insertText = item.label;
+			return item.label;
 		}
+	}
 
-		// 'overwrite[Before|After]'-logic
-		let range: vscode.Range;
+	private convertInsertTextRules(item: vscode.CompletionItem): modes.CompletionItemInsertTextRule {
+		let rules: modes.CompletionItemInsertTextRule = 0;
+		if (item.keepWhitespace) {
+			rules |= modes.CompletionItemInsertTextRule.KeepWhitespace;
+		}
+		if (item.insertText instanceof SnippetString) {
+			rules |= modes.CompletionItemInsertTextRule.InsertAsSnippet;
+		}
+		return rules;
+	}
+
+	private getRange(item: vscode.CompletionItem, defaultRange: vscode.Range) {
 		if (item.textEdit) {
-			range = item.textEdit.range;
+			return item.textEdit.range;
 		} else if (item.range) {
-			range = item.range;
+			return item.range;
 		} else {
-			range = defaultRange;
+			return defaultRange;
 		}
-		result.range = typeConvert.Range.from(range);
-
-		if (!range.isSingleLine || range.start.line !== position.line) {
-			console.warn('INVALID text edit -> must be single line and on the same line');
-			return undefined;
-		}
-
-		return result;
 	}
 }
 
@@ -1140,7 +1148,7 @@ export class ExtHostLanguageFeatures implements ExtHostLanguageFeaturesShape {
 		this._proxy.$registerCodeInsetSupport(handle, this._transformDocumentSelector(selector), eventHandle);
 		let result = this._createDisposable(handle);
 
-		if (eventHandle !== undefined) {
+		if (eventHandle !== undefined && provider.onDidChangeCodeInsets) {
 			const subscription = provider.onDidChangeCodeInsets(_ => this._proxy.$emitCodeLensEvent(eventHandle));
 			result = Disposable.from(result, subscription);
 		}
@@ -1148,7 +1156,7 @@ export class ExtHostLanguageFeatures implements ExtHostLanguageFeaturesShape {
 		return result;
 	}
 
-	$provideCodeInsets(handle: number, resource: UriComponents, token: CancellationToken): Promise<codeInset.ICodeInsetSymbol[]> {
+	$provideCodeInsets(handle: number, resource: UriComponents, token: CancellationToken): Promise<codeInset.ICodeInsetSymbol[] | undefined> {
 		return this._withAdapter(handle, CodeInsetAdapter, adapter => adapter.provideCodeInsets(URI.revive(resource), token));
 	}
 
@@ -1328,7 +1336,7 @@ export class ExtHostLanguageFeatures implements ExtHostLanguageFeaturesShape {
 		return this._createDisposable(handle);
 	}
 
-	$provideCompletionItems(handle: number, resource: UriComponents, position: IPosition, context: modes.CompletionContext, token: CancellationToken): Promise<SuggestResultDto> {
+	$provideCompletionItems(handle: number, resource: UriComponents, position: IPosition, context: modes.CompletionContext, token: CancellationToken): Promise<SuggestResultDto | undefined> {
 		return this._withAdapter(handle, SuggestAdapter, adapter => adapter.provideCompletionItems(URI.revive(resource), position, context, token));
 	}
 
@@ -1411,12 +1419,6 @@ export class ExtHostLanguageFeatures implements ExtHostLanguageFeaturesShape {
 	// --- configuration
 
 	private static _serializeRegExp(regExp: RegExp): ISerializedRegExp {
-		if (typeof regExp === 'undefined') {
-			return undefined;
-		}
-		if (regExp === null) {
-			return null;
-		}
 		return {
 			pattern: regExp.source,
 			flags: regExpFlags(regExp),
@@ -1424,36 +1426,24 @@ export class ExtHostLanguageFeatures implements ExtHostLanguageFeaturesShape {
 	}
 
 	private static _serializeIndentationRule(indentationRule: vscode.IndentationRule): ISerializedIndentationRule {
-		if (typeof indentationRule === 'undefined') {
-			return undefined;
-		}
-		if (indentationRule === null) {
-			return null;
-		}
 		return {
 			decreaseIndentPattern: ExtHostLanguageFeatures._serializeRegExp(indentationRule.decreaseIndentPattern),
 			increaseIndentPattern: ExtHostLanguageFeatures._serializeRegExp(indentationRule.increaseIndentPattern),
-			indentNextLinePattern: ExtHostLanguageFeatures._serializeRegExp(indentationRule.indentNextLinePattern),
-			unIndentedLinePattern: ExtHostLanguageFeatures._serializeRegExp(indentationRule.unIndentedLinePattern),
+			indentNextLinePattern: indentationRule.indentNextLinePattern ? ExtHostLanguageFeatures._serializeRegExp(indentationRule.indentNextLinePattern) : undefined,
+			unIndentedLinePattern: indentationRule.unIndentedLinePattern ? ExtHostLanguageFeatures._serializeRegExp(indentationRule.unIndentedLinePattern) : undefined,
 		};
 	}
 
 	private static _serializeOnEnterRule(onEnterRule: vscode.OnEnterRule): ISerializedOnEnterRule {
 		return {
 			beforeText: ExtHostLanguageFeatures._serializeRegExp(onEnterRule.beforeText),
-			afterText: ExtHostLanguageFeatures._serializeRegExp(onEnterRule.afterText),
-			oneLineAboveText: ExtHostLanguageFeatures._serializeRegExp(onEnterRule.oneLineAboveText),
+			afterText: onEnterRule.afterText ? ExtHostLanguageFeatures._serializeRegExp(onEnterRule.afterText) : undefined,
+			oneLineAboveText: onEnterRule.oneLineAboveText ? ExtHostLanguageFeatures._serializeRegExp(onEnterRule.oneLineAboveText) : undefined,
 			action: onEnterRule.action
 		};
 	}
 
-	private static _serializeOnEnterRules(onEnterRules: vscode.OnEnterRule[]): ISerializedOnEnterRule[] | undefined | null {
-		if (typeof onEnterRules === 'undefined') {
-			return undefined;
-		}
-		if (onEnterRules === null) {
-			return null;
-		}
+	private static _serializeOnEnterRules(onEnterRules: vscode.OnEnterRule[]): ISerializedOnEnterRule[] {
 		return onEnterRules.map(ExtHostLanguageFeatures._serializeOnEnterRule);
 	}
 
@@ -1476,9 +1466,9 @@ export class ExtHostLanguageFeatures implements ExtHostLanguageFeaturesShape {
 		const serializedConfiguration: ISerializedLanguageConfiguration = {
 			comments: configuration.comments,
 			brackets: configuration.brackets,
-			wordPattern: ExtHostLanguageFeatures._serializeRegExp(configuration.wordPattern),
-			indentationRules: ExtHostLanguageFeatures._serializeIndentationRule(configuration.indentationRules),
-			onEnterRules: ExtHostLanguageFeatures._serializeOnEnterRules(configuration.onEnterRules),
+			wordPattern: configuration.wordPattern ? ExtHostLanguageFeatures._serializeRegExp(configuration.wordPattern) : undefined,
+			indentationRules: configuration.indentationRules ? ExtHostLanguageFeatures._serializeIndentationRule(configuration.indentationRules) : undefined,
+			onEnterRules: configuration.onEnterRules ? ExtHostLanguageFeatures._serializeOnEnterRules(configuration.onEnterRules) : undefined,
 			__electricCharacterSupport: configuration.__electricCharacterSupport,
 			__characterPairSupport: configuration.__characterPairSupport,
 		};