diff --git a/src/tsconfig.strictNullChecks.json b/src/tsconfig.strictNullChecks.json
index 4028b21f89c..c8f807a4283 100644
--- a/src/tsconfig.strictNullChecks.json
+++ b/src/tsconfig.strictNullChecks.json
@@ -76,12 +76,15 @@
 		"./vs/workbench/api/electron-browser/mainThreadWorkspace.ts",
 		"./vs/workbench/api/node/apiCommands.ts",
 		"./vs/workbench/api/node/extHost.protocol.ts",
+		"./vs/workbench/api/node/extHostCLIServer.ts",
 		"./vs/workbench/api/node/extHostClipboard.ts",
+		"./vs/workbench/api/node/extHostCommands.ts",
 		"./vs/workbench/api/node/extHostConfiguration.ts",
 		"./vs/workbench/api/node/extHostDecorations.ts",
 		"./vs/workbench/api/node/extHostDialogs.ts",
 		"./vs/workbench/api/node/extHostDocumentContentProviders.ts",
 		"./vs/workbench/api/node/extHostDocumentData.ts",
+		"./vs/workbench/api/node/extHostDocumentSaveParticipant.ts",
 		"./vs/workbench/api/node/extHostDocuments.ts",
 		"./vs/workbench/api/node/extHostDocumentsAndEditors.ts",
 		"./vs/workbench/api/node/extHostExtensionActivator.ts",
@@ -96,6 +99,7 @@
 		"./vs/workbench/api/node/extHostSearch.ts",
 		"./vs/workbench/api/node/extHostStorage.ts",
 		"./vs/workbench/api/node/extHostTextEditor.ts",
+		"./vs/workbench/api/node/extHostTextEditors.ts",
 		"./vs/workbench/api/node/extHostTypeConverters.ts",
 		"./vs/workbench/api/node/extHostTypes.ts",
 		"./vs/workbench/api/node/extHostUrls.ts",
diff --git a/src/vs/workbench/api/node/extHostCLIServer.ts b/src/vs/workbench/api/node/extHostCLIServer.ts
index 89f6c02d448..a2311b7f69e 100644
--- a/src/vs/workbench/api/node/extHostCLIServer.ts
+++ b/src/vs/workbench/api/node/extHostCLIServer.ts
@@ -39,7 +39,7 @@ export class CLIServer {
 			console.error('Could not start open from terminal server.');
 		}
 
-		return this.ipcHandlePath;
+		return this._ipcHandlePath;
 	}
 	private collectURIToOpen(strs: string[], typeHint: URIType, result: IURIToOpen[]): void {
 		if (Array.isArray(strs)) {
diff --git a/src/vs/workbench/api/node/extHostCommands.ts b/src/vs/workbench/api/node/extHostCommands.ts
index cc707471087..acf75cefcfb 100644
--- a/src/vs/workbench/api/node/extHostCommands.ts
+++ b/src/vs/workbench/api/node/extHostCommands.ts
@@ -22,7 +22,7 @@ import { URI } from 'vs/base/common/uri';
 interface CommandHandler {
 	callback: Function;
 	thisArg: any;
-	description: ICommandHandlerDescription;
+	description?: ICommandHandlerDescription;
 }
 
 export interface ArgumentProcessor {
diff --git a/src/vs/workbench/api/node/extHostDocumentSaveParticipant.ts b/src/vs/workbench/api/node/extHostDocumentSaveParticipant.ts
index 065e9e61a48..d8a99d2aaee 100644
--- a/src/vs/workbench/api/node/extHostDocumentSaveParticipant.ts
+++ b/src/vs/workbench/api/node/extHostDocumentSaveParticipant.ts
@@ -60,7 +60,7 @@ export class ExtHostDocumentSaveParticipant implements ExtHostDocumentSavePartic
 
 				if (didTimeout) {
 					// timeout - no more listeners
-					return undefined;
+					return Promise.resolve();
 				}
 
 				const document = this._documents.getDocument(resource);
diff --git a/src/vs/workbench/api/node/extHostTextEditors.ts b/src/vs/workbench/api/node/extHostTextEditors.ts
index 3b316662afb..5e6e2dfb5a1 100644
--- a/src/vs/workbench/api/node/extHostTextEditors.ts
+++ b/src/vs/workbench/api/node/extHostTextEditors.ts
@@ -97,6 +97,9 @@ export class ExtHostEditors implements ExtHostEditorsShape {
 
 	$acceptEditorPropertiesChanged(id: string, data: IEditorPropertiesChangeData): void {
 		const textEditor = this._extHostDocumentsAndEditors.getEditor(id);
+		if (!textEditor) {
+			throw new Error('unknown text editor');
+		}
 
 		// (1) set all properties
 		if (data.options) {
@@ -137,9 +140,12 @@ export class ExtHostEditors implements ExtHostEditorsShape {
 	}
 
 	$acceptEditorPositionData(data: ITextEditorPositionData): void {
-		for (let id in data) {
-			let textEditor = this._extHostDocumentsAndEditors.getEditor(id);
-			let viewColumn = TypeConverters.ViewColumn.to(data[id]);
+		for (const id in data) {
+			const textEditor = this._extHostDocumentsAndEditors.getEditor(id);
+			if (!textEditor) {
+				throw new Error('Unknown text editor');
+			}
+			const viewColumn = TypeConverters.ViewColumn.to(data[id]);
 			if (textEditor.viewColumn !== viewColumn) {
 				textEditor._acceptViewColumn(viewColumn);
 				this._onDidChangeTextEditorViewColumn.fire({ textEditor, viewColumn });