fix some TS 4.1 errors (#106358)

Author: bpasero

src/vs/workbench/api/browser/mainThreadMessageService.ts

@@ -39,9 +39,9 @@ export class MainThreadMessageService implements MainThreadMessageServiceShape {
 		}
 	}
 
-	private _showMessage(severity: Severity, message: string, commands: { title: string; isCloseAffordance: boolean; handle: number; }[], extension: IExtensionDescription | undefined): Promise<number> {
+	private _showMessage(severity: Severity, message: string, commands: { title: string; isCloseAffordance: boolean; handle: number; }[], extension: IExtensionDescription | undefined): Promise<number | undefined> {
 
-		return new Promise<number>(resolve => {
+		return new Promise<number | undefined>(resolve => {
 
 			const primaryActions: MessageItemAction[] = [];
 

src/vs/workbench/services/progress/browser/progressService.ts

@@ -224,9 +224,9 @@ export class ProgressService extends Disposable implements IProgressService {
 			// Create a promise that we can resolve as needed
 			// when the outside calls dispose on us
 			let promiseResolve: () => void;
-			const promise = new Promise<R>(resolve => promiseResolve = resolve);
+			const promise = new Promise<void>(resolve => promiseResolve = resolve);
 
-			this.withWindowProgress<R>({
+			this.withWindowProgress({
 				location: ProgressLocation.Window,
 				title: options.title ? parseLinkedText(options.title).toString() : undefined, // convert markdown links => string
 				command: 'notifications.showList'

src/vs/workbench/services/workspaces/browser/abstractWorkspaceEditingService.ts

@@ -307,7 +307,7 @@ export abstract class AbstractWorkspaceEditingService implements IWorkspaceEditi
 		);
 	}
 
-	abstract async enterWorkspace(path: URI): Promise<void>;
+	abstract enterWorkspace(path: URI): Promise<void>;
 
 	protected async doEnterWorkspace(path: URI): Promise<IEnterWorkspaceResult | null> {
 		if (!!this.environmentService.extensionTestsLocationURI) {