Fix #107660

src/vs/code/browser/workbench/workbench.ts

@@ -494,8 +494,8 @@ class WindowIndicator implements IWindowIndicator {
 	};
 
 	// settings sync options
-	const settingsSyncOptions: ISettingsSyncOptions = {
-		enabled: !!config.settingsSyncOptions?.enabled,
+	const settingsSyncOptions: ISettingsSyncOptions | undefined = config.settingsSyncOptions ? {
+		enabled: config.settingsSyncOptions.enabled,
 		enablementHandler: (enablement) => {
 			let queryString = `settingsSync=${enablement ? 'true' : 'false'}`;
 
@@ -509,7 +509,7 @@ class WindowIndicator implements IWindowIndicator {
 
 			window.location.href = `${window.location.origin}?${queryString}`;
 		}
-	};
+	} : undefined;
 
 	// Finally create workbench
 	create(document.body, {

src/vs/workbench/services/userDataSync/browser/userDataAutoSyncService.ts

@@ -25,8 +25,12 @@ export class WebUserDataAutoSyncService extends UserDataAutoSyncService implemen
 	protected setEnablement(enabled: boolean) {
 		if (this.enabled !== enabled) {
 			this.enabled = enabled;
-			if (this.workbenchEnvironmentService.options?.settingsSyncOptions?.enablementHandler) {
-				this.workbenchEnvironmentService.options.settingsSyncOptions.enablementHandler(this.enabled);
+			if (this.workbenchEnvironmentService.options?.settingsSyncOptions) {
+				if (this.workbenchEnvironmentService.options.settingsSyncOptions?.enablementHandler) {
+					this.workbenchEnvironmentService.options.settingsSyncOptions.enablementHandler(this.enabled);
+				}
+			} else {
+				super.setEnablement(enabled);
 			}
 		}
 	}