Address some null errors (#60565)

src/vs/editor/common/modes.ts

@@ -1317,7 +1317,7 @@ export interface DocumentCommentProvider {
 	deleteReaction?(resource: URI, comment: Comment, reaction: CommentReaction, token: CancellationToken): Promise<void>;
 	reactionGroup?: CommentReaction[];
 
-	onDidChangeCommentThreads(): Event<CommentThreadChangedEvent>;
+	onDidChangeCommentThreads?(): Event<CommentThreadChangedEvent>;
 }
 
 /**

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

@@ -75,7 +75,7 @@ export class MainThreadDocumentCommentProvider implements modes.DocumentCommentP
 	}
 
 
-	onDidChangeCommentThreads = null;
+	// onDidChangeCommentThreads = null;
 }
 
 @extHostNamedCustomer(MainContext.MainThreadComments)
@@ -129,8 +129,10 @@ export class MainThreadComments extends Disposable implements MainThreadComments
 						});
 					});
 
-					this._openPanelListener.dispose();
-					this._openPanelListener = null;
+					if (this._openPanelListener) {
+						this._openPanelListener.dispose();
+						this._openPanelListener = null;
+					}
 				}
 			});
 		}

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

@@ -85,8 +85,8 @@ class DocumentAndEditorStateDelta {
 		readonly addedDocuments: ITextModel[],
 		readonly removedEditors: TextEditorSnapshot[],
 		readonly addedEditors: TextEditorSnapshot[],
-		readonly oldActiveEditor: string | undefined,
-		readonly newActiveEditor: string | undefined,
+		readonly oldActiveEditor: string | null | undefined,
+		readonly newActiveEditor: string | null | undefined,
 	) {
 		this.isEmpty = this.removedDocuments.length === 0
 			&& this.addedDocuments.length === 0
@@ -131,7 +131,7 @@ class DocumentAndEditorState {
 	constructor(
 		readonly documents: Set<ITextModel>,
 		readonly textEditors: Map<string, TextEditorSnapshot>,
-		readonly activeEditor: string | undefined,
+		readonly activeEditor: string | null | undefined,
 	) {
 		//
 	}
@@ -257,7 +257,7 @@ class MainThreadDocumentAndEditorStateComputer {
 		// to match output panels or the active workbench editor with
 		// one of editor we have just computed
 		if (!activeEditor) {
-			let candidate: IEditor;
+			let candidate: IEditor | undefined;
 			if (this._activeEditorOrder === ActiveEditorOrder.Editor) {
 				candidate = this._getActiveEditorFromEditorPart() || this._getActiveEditorFromPanel();
 			} else {
@@ -291,7 +291,7 @@ class MainThreadDocumentAndEditorStateComputer {
 		}
 	}
 
-	private _getActiveEditorFromEditorPart(): IEditor {
+	private _getActiveEditorFromEditorPart(): IEditor | undefined {
 		let result = this._editorService.activeTextEditorWidget;
 		if (isDiffEditor(result)) {
 			result = result.getModifiedEditor();

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

@@ -87,9 +87,10 @@ export class MainThreadLanguageFeatures implements MainThreadLanguageFeaturesSha
 
 	private static _reviveWorkspaceSymbolDto(data: WorkspaceSymbolDto): search.IWorkspaceSymbol;
 	private static _reviveWorkspaceSymbolDto(data: WorkspaceSymbolDto[]): search.IWorkspaceSymbol[];
-	private static _reviveWorkspaceSymbolDto(data: WorkspaceSymbolDto | WorkspaceSymbolDto[]): search.IWorkspaceSymbol | search.IWorkspaceSymbol[] {
+	private static _reviveWorkspaceSymbolDto(data: undefined): undefined;
+	private static _reviveWorkspaceSymbolDto(data: WorkspaceSymbolDto | WorkspaceSymbolDto[] | undefined): search.IWorkspaceSymbol | search.IWorkspaceSymbol[] | undefined {
 		if (!data) {
-			return <search.IWorkspaceSymbol>data;
+			return <undefined>data;
 		} else if (Array.isArray(data)) {
 			data.forEach(MainThreadLanguageFeatures._reviveWorkspaceSymbolDto);
 			return <search.IWorkspaceSymbol[]>data;
@@ -99,7 +100,7 @@ export class MainThreadLanguageFeatures implements MainThreadLanguageFeaturesSha
 		}
 	}
 
-	private static _reviveCodeActionDto(data: CodeActionDto[]): modes.CodeAction[] {
+	private static _reviveCodeActionDto(data: CodeActionDto[] | undefined): modes.CodeAction[] {
 		if (data) {
 			data.forEach(code => reviveWorkspaceEditDto(code.edit));
 		}

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

@@ -558,9 +558,9 @@ export interface MainThreadTaskShape extends IDisposable {
 
 export interface MainThreadExtensionServiceShape extends IDisposable {
 	$localShowMessage(severity: Severity, msg: string): void;
-	$activateExtension(extensionId: ExtensionIdentifier, activationEvent: string): Promise<void>;
+	$activateExtension(extensionId: ExtensionIdentifier, activationEvent: string | null): Promise<void>;
 	$onWillActivateExtension(extensionId: ExtensionIdentifier): void;
-	$onDidActivateExtension(extensionId: ExtensionIdentifier, startup: boolean, codeLoadingTime: number, activateCallTime: number, activateResolvedTime: number, activationEvent: string): void;
+	$onDidActivateExtension(extensionId: ExtensionIdentifier, startup: boolean, codeLoadingTime: number, activateCallTime: number, activateResolvedTime: number, activationEvent: string | null): void;
 	$onExtensionActivationFailed(extensionId: ExtensionIdentifier): void;
 	$onExtensionRuntimeError(extensionId: ExtensionIdentifier, error: SerializedError): void;
 	$addMessage(extensionId: ExtensionIdentifier, severity: Severity, message: string): void;
@@ -691,7 +691,7 @@ export interface ITextEditorAddData {
 	options: IResolvedTextEditorConfiguration;
 	selections: ISelection[];
 	visibleRanges: IRange[];
-	editorPosition: EditorViewColumn;
+	editorPosition: EditorViewColumn | undefined;
 }
 export interface ITextEditorPositionData {
 	[id: string]: EditorViewColumn;
@@ -716,7 +716,7 @@ export interface IDocumentsAndEditorsDelta {
 	addedDocuments?: IModelAddedData[];
 	removedEditors?: string[];
 	addedEditors?: ITextEditorAddData[];
-	newActiveEditor?: string;
+	newActiveEditor?: string | null;
 }
 
 export interface ExtHostDocumentsAndEditorsShape {
@@ -867,7 +867,7 @@ export interface WorkspaceEditDto {
 	rejectReason?: string;
 }
 
-export function reviveWorkspaceEditDto(data: WorkspaceEditDto): modes.WorkspaceEdit {
+export function reviveWorkspaceEditDto(data: WorkspaceEditDto | undefined): modes.WorkspaceEdit {
 	if (data && data.edits) {
 		for (const edit of data.edits) {
 			if (typeof (<ResourceTextEditDto>edit).resource === 'object') {

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

@@ -166,7 +166,7 @@ export class ExtHostExtensionService implements ExtHostExtensionServiceShape {
 	private readonly _storage: ExtHostStorage;
 	private readonly _storagePath: ExtensionStoragePath;
 	private readonly _activator: ExtensionsActivator;
-	private _extensionPathIndex: Promise<TernarySearchTree<IExtensionDescription>>;
+	private _extensionPathIndex: Promise<TernarySearchTree<IExtensionDescription>> | null;
 	private readonly _extensionApiFactory: IExtensionApiFactory;
 
 	private readonly _resolvers: { [authorityPrefix: string]: vscode.RemoteAuthorityResolver; };
@@ -222,7 +222,7 @@ export class ExtHostExtensionService implements ExtHostExtensionServiceShape {
 					await this._mainThreadExtensionsProxy.$activateExtension(extensionId, activationEvent);
 					return new HostExtension();
 				}
-				const extensionDescription = this._registry.getExtensionDescription(extensionId);
+				const extensionDescription = this._registry.getExtensionDescription(extensionId)!;
 				return this._activateExtension(extensionDescription, reason);
 			}
 		});
@@ -302,7 +302,7 @@ export class ExtHostExtensionService implements ExtHostExtensionServiceShape {
 		return this._barrier.wait().then(_ => this._registry);
 	}
 
-	public getExtensionExports(extensionId: ExtensionIdentifier): IExtensionAPI {
+	public getExtensionExports(extensionId: ExtensionIdentifier): IExtensionAPI | null | undefined {
 		if (this._barrier.isOpen()) {
 			return this._activator.getActivatedExtension(extensionId).exports;
 		} else {
@@ -624,7 +624,7 @@ export class ExtHostExtensionService implements ExtHostExtensionServiceShape {
 		// Execute the runner if it follows our spec
 		if (testRunner && typeof testRunner.run === 'function') {
 			return new Promise<void>((c, e) => {
-				testRunner!.run(this._initData.environment.extensionTestsPath, (error, failures) => {
+				testRunner!.run(this._initData.environment.extensionTestsPath!, (error, failures) => {
 					if (error) {
 						e(error.toString());
 					} else {
@@ -671,7 +671,7 @@ export class ExtHostExtensionService implements ExtHostExtensionServiceShape {
 	public registerRemoteAuthorityResolver(authorityPrefix: string, resolver: vscode.RemoteAuthorityResolver): vscode.Disposable {
 		this._resolvers[authorityPrefix] = resolver;
 		return toDisposable(() => {
-			this._resolvers[authorityPrefix] = null;
+			delete this._resolvers[authorityPrefix];
 		});
 	}
 

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

@@ -53,8 +53,8 @@ export class ExtHostEditors implements ExtHostEditorsShape {
 
 	showTextDocument(document: vscode.TextDocument, column: vscode.ViewColumn, preserveFocus: boolean): Promise<vscode.TextEditor>;
 	showTextDocument(document: vscode.TextDocument, options: { column: vscode.ViewColumn, preserveFocus: boolean, pinned: boolean }): Promise<vscode.TextEditor>;
-	showTextDocument(document: vscode.TextDocument, columnOrOptions: vscode.ViewColumn | vscode.TextDocumentShowOptions, preserveFocus?: boolean): Promise<vscode.TextEditor>;
-	showTextDocument(document: vscode.TextDocument, columnOrOptions: vscode.ViewColumn | vscode.TextDocumentShowOptions, preserveFocus?: boolean): Promise<vscode.TextEditor> {
+	showTextDocument(document: vscode.TextDocument, columnOrOptions: vscode.ViewColumn | vscode.TextDocumentShowOptions | undefined, preserveFocus?: boolean): Promise<vscode.TextEditor>;
+	showTextDocument(document: vscode.TextDocument, columnOrOptions: vscode.ViewColumn | vscode.TextDocumentShowOptions | undefined, preserveFocus?: boolean): Promise<vscode.TextEditor> {
 		let options: ITextDocumentShowOptions;
 		if (typeof columnOrOptions === 'number') {
 			options = {