diff --git a/src/vs/workbench/api/common/extHostDocuments.ts b/src/vs/workbench/api/common/extHostDocuments.ts
index ea9e189ce51ca2a9f81e60e111734efd6bde04f1..60a0e162e36232772ff74f8d7887ac095fe45ccf 100644
--- a/src/vs/workbench/api/common/extHostDocuments.ts
+++ b/src/vs/workbench/api/common/extHostDocuments.ts
@@ -12,6 +12,7 @@ import { ExtHostDocumentData, setWordDefinitionFor } from 'vs/workbench/api/comm
 import { ExtHostDocumentsAndEditors } from 'vs/workbench/api/common/extHostDocumentsAndEditors';
 import * as TypeConverters from 'vs/workbench/api/common/extHostTypeConverters';
 import * as vscode from 'vscode';
+import { assertIsDefined } from 'vs/base/common/types';
 
 export class ExtHostDocuments implements ExtHostDocumentsShape {
 
@@ -84,7 +85,7 @@ export class ExtHostDocuments implements ExtHostDocumentsShape {
 		if (!promise) {
 			promise = this._proxy.$tryOpenDocument(uri).then(() => {
 				this._documentLoader.delete(uri.toString());
-				return this._documentsAndEditors.getDocument(uri);
+				return assertIsDefined(this._documentsAndEditors.getDocument(uri));
 			}, err => {
 				this._documentLoader.delete(uri.toString());
 				return Promise.reject(err);
diff --git a/src/vs/workbench/api/node/extHostDebugService.ts b/src/vs/workbench/api/node/extHostDebugService.ts
index f4a7d7eed8f2ec368899c0938d1d1d8c82261f55..1b9b233961a84f75c39c0e4c99c7bf69eb798ba2 100644
--- a/src/vs/workbench/api/node/extHostDebugService.ts
+++ b/src/vs/workbench/api/node/extHostDebugService.ts
@@ -383,7 +383,7 @@ export class ExtHostDebugService implements IExtHostDebugService, ExtHostDebugSe
 	public async $substituteVariables(folderUri: UriComponents | undefined, config: IConfig): Promise<IConfig> {
 		if (!this._variableResolver) {
 			const [workspaceFolders, configProvider] = await Promise.all([this._workspaceService.getWorkspaceFolders2(), this._configurationService.getConfigProvider()]);
-			this._variableResolver = new ExtHostVariableResolverService(workspaceFolders || [], this._editorsService, configProvider);
+			this._variableResolver = new ExtHostVariableResolverService(workspaceFolders || [], this._editorsService, configProvider!);
 		}
 		let ws: IWorkspaceFolder | undefined;
 		const folder = await this.getFolder(folderUri);
@@ -783,7 +783,7 @@ export class ExtHostDebugService implements IExtHostDebugService, ExtHostDebugSe
 				}
 				return undefined;
 			}),
-			new Promise((resolve, reject) => {
+			new Promise<never>((resolve, reject) => {
 				const timeout = setTimeout(() => {
 					clearTimeout(timeout);
 					reject(new Error('timeout'));
diff --git a/src/vs/workbench/api/node/extHostExtensionService.ts b/src/vs/workbench/api/node/extHostExtensionService.ts
index 49a8e254fd5a33fb9987a6458ea04da5f725bc97..a1c3e50ffdc4557302430d3bf7f1c117751ffd6d 100644
--- a/src/vs/workbench/api/node/extHostExtensionService.ts
+++ b/src/vs/workbench/api/node/extHostExtensionService.ts
@@ -72,6 +72,7 @@ export class ExtHostExtensionService extends AbstractExtHostExtensionService {
 				return nativeProcessSend.apply(process, args);
 			}
 			mainThreadConsole.$logExtensionHostMessage(args[0]);
+			return false;
 		};
 	}
 
diff --git a/src/vs/workbench/contrib/preferences/browser/settingsEditor2.ts b/src/vs/workbench/contrib/preferences/browser/settingsEditor2.ts
index 94a818f25e9bdb1df4ff7c4e2ec735884ae077bc..f8d98b3d05c71c08bc8e2a41389ce3f36d67627c 100644
--- a/src/vs/workbench/contrib/preferences/browser/settingsEditor2.ts
+++ b/src/vs/workbench/contrib/preferences/browser/settingsEditor2.ts
@@ -1305,7 +1305,7 @@ export class SettingsEditor2 extends BaseEditor {
 	private _filterOrSearchPreferencesModel(filter: string, model: ISettingsEditorModel, provider?: ISearchProvider, token?: CancellationToken): Promise<ISearchResult | null> {
 		const searchP = provider ? provider.searchModel(model, token) : Promise.resolve(null);
 		return searchP
-			.then<ISearchResult>(null, err => {
+			.then<ISearchResult, ISearchResult | null>(undefined, err => {
 				if (isPromiseCanceledError(err)) {
 					return Promise.reject(err);
 				} else {
@@ -1321,7 +1321,7 @@ export class SettingsEditor2 extends BaseEditor {
 						this.telemetryService.publicLog('settingsEditor.searchError', { message, filter });
 						this.logService.info('Setting search error: ' + message);
 					}
-					return Promise.resolve(null);
+					return null;
 				}
 			});
 	}
diff --git a/src/vs/workbench/contrib/terminal/node/terminalProcess.ts b/src/vs/workbench/contrib/terminal/node/terminalProcess.ts
index 0c29deb75fa8d6860c90ae72f4099eb5b2092205..8456a0fdd4151b19bd4a0a8cf2ac6eb6cb67610b 100644
--- a/src/vs/workbench/contrib/terminal/node/terminalProcess.ts
+++ b/src/vs/workbench/contrib/terminal/node/terminalProcess.ts
@@ -74,18 +74,21 @@ export class TerminalProcess extends Disposable implements ITerminalChildProcess
 			if (!stat.isDirectory()) {
 				return Promise.reject(SHELL_CWD_INVALID_EXIT_CODE);
 			}
+			return undefined;
 		}, async err => {
 			if (err && err.code === 'ENOENT') {
 				// So we can include in the error message the specified CWD
 				shellLaunchConfig.cwd = cwd;
 				return Promise.reject(SHELL_CWD_INVALID_EXIT_CODE);
 			}
+			return undefined;
 		});
 
 		const executableVerification = stat(shellLaunchConfig.executable!).then(async stat => {
 			if (!stat.isFile() && !stat.isSymbolicLink()) {
 				return Promise.reject(stat.isDirectory() ? SHELL_PATH_DIRECTORY_EXIT_CODE : SHELL_PATH_INVALID_EXIT_CODE);
 			}
+			return undefined;
 		}, async (err) => {
 			if (err && err.code === 'ENOENT') {
 				let cwd = shellLaunchConfig.cwd instanceof URI ? shellLaunchConfig.cwd.path : shellLaunchConfig.cwd!;
@@ -96,6 +99,7 @@ export class TerminalProcess extends Disposable implements ITerminalChildProcess
 					return Promise.reject(SHELL_PATH_INVALID_EXIT_CODE);
 				}
 			}
+			return undefined;
 		});
 
 		Promise.all([cwdVerification, executableVerification]).then(() => {