Strict null check sidebarPart

src/tsconfig.strictNullChecks.json

@@ -548,6 +548,7 @@
 		"./vs/workbench/browser/parts/quickinput/quickInputBox.ts",
 		"./vs/workbench/browser/parts/quickinput/quickInputUtils.ts",
 		"./vs/workbench/browser/parts/quickopen/quickopen.ts",
+		"./vs/workbench/browser/parts/sidebar/sidebarPart.ts",
 		"./vs/workbench/browser/parts/statusbar/statusbar.ts",
 		"./vs/workbench/browser/parts/statusbar/statusbarPart.ts",
 		"./vs/workbench/browser/parts/views/panelViewlet.ts",

src/vs/workbench/browser/parts/sidebar/sidebarPart.ts

@@ -175,7 +175,7 @@ export class SidebarPart extends CompositePart<Viewlet> implements IViewletServi
 		}
 	}
 
-	openViewlet(id: string, focus?: boolean): Promise<IViewlet> {
+	openViewlet(id: string, focus?: boolean): Promise<IViewlet | null> {
 		if (this.getViewlet(id)) {
 			return Promise.resolve(this.doOpenViewlet(id, focus));
 		}
@@ -195,7 +195,7 @@ export class SidebarPart extends CompositePart<Viewlet> implements IViewletServi
 
 	getAllViewlets(): ViewletDescriptor[] {
 		return this.viewletRegistry.getViewlets()
-			.sort((v1, v2) => v1.order - v2.order);
+			.sort((v1, v2) => v1.order! - v2.order!);
 	}
 
 	getDefaultViewletId(): string {
@@ -206,7 +206,7 @@ export class SidebarPart extends CompositePart<Viewlet> implements IViewletServi
 		return this.getViewlets().filter(viewlet => viewlet.id === id)[0];
 	}
 
-	private doOpenViewlet(id: string, focus?: boolean): Viewlet {
+	private doOpenViewlet(id: string, focus?: boolean): Viewlet | null {
 		if (this.blockOpeningViewlet) {
 			return null; // Workaround against a potential race condition
 		}

src/vs/workbench/electron-browser/actions.ts

@@ -768,7 +768,8 @@ export abstract class BaseNavigationAction extends Action {
 
 		const activeViewletId = this.viewletService.getActiveViewlet().getId();
 
-		return this.viewletService.openViewlet(activeViewletId, true);
+		return this.viewletService.openViewlet(activeViewletId, true)
+			.then(value => value === null ? false : value);
 	}
 
 	protected navigateAcrossEditorGroup(direction: GroupDirection): boolean {

src/vs/workbench/services/viewlet/browser/viewlet.ts

@@ -22,7 +22,7 @@ export interface IViewletService {
 	/**
 	 * Opens a viewlet with the given identifier and pass keyboard focus to it if specified.
 	 */
-	openViewlet(id: string, focus?: boolean): Promise<IViewlet>;
+	openViewlet(id: string, focus?: boolean): Promise<IViewlet | null>;
 
 	/**
 	 * Returns the current active viewlet or null if none.