diff --git a/src/vs/base/browser/globalMouseMoveMonitor.ts b/src/vs/base/browser/globalMouseMoveMonitor.ts
index 4ab9a6c2d33..cc8474f39ee 100644
--- a/src/vs/base/browser/globalMouseMoveMonitor.ts
+++ b/src/vs/base/browser/globalMouseMoveMonitor.ts
@@ -27,7 +27,7 @@ export interface IOnStopCallback {
 	(): void;
 }
 
-export function standardMouseMoveMerger(lastEvent: IStandardMouseMoveEventData, currentEvent: MouseEvent): IStandardMouseMoveEventData {
+export function standardMouseMoveMerger(lastEvent: IStandardMouseMoveEventData | null, currentEvent: MouseEvent): IStandardMouseMoveEventData {
 	let ev = new StandardMouseEvent(currentEvent);
 	ev.preventDefault();
 	return {
diff --git a/src/vs/editor/browser/editorExtensions.ts b/src/vs/editor/browser/editorExtensions.ts
index 1b81608b013..2a12d008b5c 100644
--- a/src/vs/editor/browser/editorExtensions.ts
+++ b/src/vs/editor/browser/editorExtensions.ts
@@ -307,7 +307,7 @@ export function registerEditorContribution<Services extends BrandedService[]>(id
 	EditorContributionRegistry.INSTANCE.registerEditorContribution(id, ctor);
 }
 
-export function registerDiffEditorContribution(id: string, ctor: IDiffEditorContributionCtor): void {
+export function registerDiffEditorContribution<Services extends BrandedService[]>(id: string, ctor: { new(editor: IDiffEditor, ...services: Services): IEditorContribution }): void {
 	EditorContributionRegistry.INSTANCE.registerDiffEditorContribution(id, ctor);
 }
 
@@ -363,7 +363,7 @@ class EditorContributionRegistry {
 		return this.editorContributions.slice(0);
 	}
 
-	public registerDiffEditorContribution(id: string, ctor: IDiffEditorContributionCtor): void {
+	public registerDiffEditorContribution<Services extends BrandedService[]>(id: string, ctor: { new(editor: IDiffEditor, ...services: Services): IEditorContribution }): void {
 		this.diffEditorContributions.push({ id, ctor });
 	}
 
diff --git a/src/vs/platform/remote/common/remoteAgentConnection.ts b/src/vs/platform/remote/common/remoteAgentConnection.ts
index b526d149fa3..eab85914921 100644
--- a/src/vs/platform/remote/common/remoteAgentConnection.ts
+++ b/src/vs/platform/remote/common/remoteAgentConnection.ts
@@ -89,8 +89,8 @@ async function connectToRemoteExtensionHostAgent(options: ISimpleConnectionOptio
 			options.host,
 			options.port,
 			`reconnectionToken=${options.reconnectionToken}&reconnection=${options.reconnectionProtocol ? 'true' : 'false'}`,
-			(err: any, socket: ISocket) => {
-				if (err) {
+			(err: any, socket: ISocket | undefined) => {
+				if (err || !socket) {
 					options.logService.error(`${logPrefix} socketFactory.connect() failed. Error:`);
 					options.logService.error(err);
 					e(err);
diff --git a/src/vs/workbench/api/common/extHost.api.impl.ts b/src/vs/workbench/api/common/extHost.api.impl.ts
index 448923b1044..e71a93d69e4 100644
--- a/src/vs/workbench/api/common/extHost.api.impl.ts
+++ b/src/vs/workbench/api/common/extHost.api.impl.ts
@@ -185,8 +185,7 @@ export function createApiFactoryAndRegisterActors(accessor: ServicesAccessor): I
 					}
 
 					return activeTextEditor.edit((edit: vscode.TextEditorEdit) => {
-						args.unshift(activeTextEditor, edit);
-						callback.apply(thisArg, args);
+						callback.apply(thisArg, [activeTextEditor, edit, ...args]);
 
 					}).then((result) => {
 						if (!result) {
diff --git a/src/vs/workbench/contrib/codeEditor/browser/suggestEnabledInput/suggestEnabledInput.ts b/src/vs/workbench/contrib/codeEditor/browser/suggestEnabledInput/suggestEnabledInput.ts
index 223949c9ac6..b7f1355fdad 100644
--- a/src/vs/workbench/contrib/codeEditor/browser/suggestEnabledInput/suggestEnabledInput.ts
+++ b/src/vs/workbench/contrib/codeEditor/browser/suggestEnabledInput/suggestEnabledInput.ts
@@ -82,7 +82,7 @@ export interface ISuggestEnabledInputStyleOverrides extends IStyleOverrides {
 }
 
 type ISuggestEnabledInputStyles = {
-	[P in keyof ISuggestEnabledInputStyleOverrides]: Color;
+	[P in keyof ISuggestEnabledInputStyleOverrides]: Color | undefined;
 };
 
 export function attachSuggestEnabledInputBoxStyler(widget: IThemable, themeService: IThemeService, style?: ISuggestEnabledInputStyleOverrides): IDisposable {
diff --git a/src/vs/workbench/services/extensions/common/extensionHostProcessManager.ts b/src/vs/workbench/services/extensions/common/extensionHostProcessManager.ts
index cb638f64361..f3b6c2bf21d 100644
--- a/src/vs/workbench/services/extensions/common/extensionHostProcessManager.ts
+++ b/src/vs/workbench/services/extensions/common/extensionHostProcessManager.ts
@@ -406,7 +406,10 @@ export class MeasureExtHostLatencyAction extends Action {
 		this._editorService.openEditor({ contents: measurements.map(MeasureExtHostLatencyAction._print).join('\n\n'), options: { pinned: true } } as IUntitledTextResourceInput);
 	}
 
-	private static _print(m: ExtHostLatencyResult): string {
+	private static _print(m: ExtHostLatencyResult | null): string {
+		if (!m) {
+			return '';
+		}
 		return `${m.remoteAuthority ? `Authority: ${m.remoteAuthority}\n` : ``}Roundtrip latency: ${m.latency.toFixed(3)}ms\nUp: ${MeasureExtHostLatencyAction._printSpeed(m.up)}\nDown: ${MeasureExtHostLatencyAction._printSpeed(m.down)}\n`;
 	}
 
diff --git a/src/vs/workbench/services/mode/common/workbenchModeService.ts b/src/vs/workbench/services/mode/common/workbenchModeService.ts
index f097879bc0d..c6033d4ef98 100644
--- a/src/vs/workbench/services/mode/common/workbenchModeService.ts
+++ b/src/vs/workbench/services/mode/common/workbenchModeService.ts
@@ -105,7 +105,7 @@ export class WorkbenchModeServiceImpl extends ModeServiceImpl {
 		this._configurationService = configurationService;
 		this._extensionService = extensionService;
 
-		languagesExtPoint.setHandler((extensions: IExtensionPointUser<IRawLanguageExtensionPoint[]>[]) => {
+		languagesExtPoint.setHandler((extensions: readonly IExtensionPointUser<IRawLanguageExtensionPoint[]>[]) => {
 			let allValidLanguages: ILanguageExtensionPoint[] = [];
 
 			for (let i = 0, len = extensions.length; i < len; i++) {