[filesystem] Fixes eclipse-theia#4792 XSS vulnerability.

Mitigates the issue by removing all unsanitized information from the
response.

Signed-off-by: Casey Flynn <caseyflynn@google.com>

Signed-off-by: Doron Nahari doron.nahari@sap.com

packages/filesystem/src/node/download/file-download-handler.ts

@@ -89,7 +89,7 @@ export abstract class FileDownloadHandler {
 
     protected async handleError(response: Response, reason: string | Error, status: number = INTERNAL_SERVER_ERROR): Promise<void> {
         this.logger.error(reason);
-        response.status(status).send(reason).end();
+        response.status(status).send('Unable to download file.').end();
     }
 
 }