diff --git a/src/tsconfig.strictNullChecks.json b/src/tsconfig.strictNullChecks.json
index ca6a379ac05..537b986479e 100644
--- a/src/tsconfig.strictNullChecks.json
+++ b/src/tsconfig.strictNullChecks.json
@@ -661,6 +661,7 @@
 		"./vs/workbench/services/decorations/browser/decorationsService.ts",
 		"./vs/workbench/services/extensions/common/extensions.ts",
 		"./vs/workbench/services/extensions/common/extensionsRegistry.ts",
+		"./vs/workbench/services/extensions/electron-browser/cachedExtensionScanner.ts",
 		"./vs/workbench/services/extensions/electron-browser/inactiveExtensionUrlHandler.ts",
 		"./vs/workbench/services/extensions/node/extensionDescriptionRegistry.ts",
 		"./vs/workbench/services/extensions/node/extensionManagementServerService.ts",
diff --git a/src/vs/workbench/services/extensions/electron-browser/cachedExtensionScanner.ts b/src/vs/workbench/services/extensions/electron-browser/cachedExtensionScanner.ts
index 4efb17e4906..4cb7a231f3b 100644
--- a/src/vs/workbench/services/extensions/electron-browser/cachedExtensionScanner.ts
+++ b/src/vs/workbench/services/extensions/electron-browser/cachedExtensionScanner.ts
@@ -123,7 +123,7 @@ export class CachedExtensionScanner {
 		);
 	}
 
-	private static async _readExtensionCache(environmentService: IEnvironmentService, cacheKey: string): Promise<IExtensionCacheData> {
+	private static async _readExtensionCache(environmentService: IEnvironmentService, cacheKey: string): Promise<IExtensionCacheData | null> {
 		const cacheFolder = path.join(environmentService.userDataPath, MANIFEST_CACHE_FOLDER);
 		const cacheFile = path.join(cacheFolder, cacheKey);
 
@@ -260,8 +260,8 @@ export class CachedExtensionScanner {
 			);
 
 			// Always load developed extensions while extensions development
-			let developedExtensions = Promise.resolve([]);
-			if (environmentService.isExtensionDevelopment && environmentService.extensionDevelopmentLocationURI.scheme === Schemas.file) {
+			let developedExtensions: Promise<IExtensionDescription[]> = Promise.resolve([]);
+			if (environmentService.isExtensionDevelopment && environmentService.extensionDevelopmentLocationURI && environmentService.extensionDevelopmentLocationURI.scheme === Schemas.file) {
 				developedExtensions = ExtensionScanner.scanOneOrMultipleExtensions(
 					new ExtensionScannerInput(version, commit, locale, devMode, fsPath(environmentService.extensionDevelopmentLocationURI), false, true, translations), log
 				);
diff --git a/src/vs/workbench/services/extensions/node/extensionPoints.ts b/src/vs/workbench/services/extensions/node/extensionPoints.ts
index d80156e5e00..50b38ceb6f2 100644
--- a/src/vs/workbench/services/extensions/node/extensionPoints.ts
+++ b/src/vs/workbench/services/extensions/node/extensionPoints.ts
@@ -49,7 +49,7 @@ namespace Translations {
 
 export interface NlsConfiguration {
 	readonly devMode: boolean;
-	readonly locale: string;
+	readonly locale: string | undefined;
 	readonly pseudo: boolean;
 	readonly translations: Translations;
 }
@@ -444,8 +444,8 @@ export class ExtensionScannerInput {
 
 	constructor(
 		public readonly ourVersion: string,
-		public readonly commit: string,
-		public readonly locale: string,
+		public readonly commit: string | undefined,
+		public readonly locale: string | undefined,
 		public readonly devMode: boolean,
 		public readonly absoluteFolderPath: string,
 		public readonly isBuiltin: boolean,