Update app.py

app.py

@@ -41,7 +41,8 @@ def run_capture(cmd):
     result = subprocess.run(cmd, stdout=subprocess.PIPE, stderr=subprocess.PIPE, text=True)
     if result.returncode != 0:
         err_tail = result.stderr[-1000:] if result.stderr else ""
-        raise RuntimeError(f"Command failed: {' '.join(cmd)}
+        raise RuntimeError("Command failed: " + " ".join(cmd) + "
+" + err_tail)
 {err_tail}")
     return result.stdout