diff --git a/src/vs/workbench/api/common/extHost.api.impl.ts b/src/vs/workbench/api/common/extHost.api.impl.ts
index 57de023e859..1f0e0c5bc3b 100644
--- a/src/vs/workbench/api/common/extHost.api.impl.ts
+++ b/src/vs/workbench/api/common/extHost.api.impl.ts
@@ -268,7 +268,7 @@ export function createApiFactoryAndRegisterActors(accessor: ServicesAccessor): I
 			get sessionId() { return initData.telemetryInfo.sessionId; },
 			get language() { return initData.environment.appLanguage; },
 			get appName() { return initData.environment.appName; },
-			get appRoot() { return initData.environment.appRoot!.fsPath; },
+			get appRoot() { return initData.environment.appRoot?.fsPath ?? '<UNKNOWN_APP_ROOT>'; },
 			get uriScheme() { return initData.environment.appUriScheme; },
 			get logLevel() {
 				checkProposedApiEnabled(extension);