Base path is empty

This might have been fixed in 📌 Automated Drupal 11 compatibility fixes for error_page Needs review . Could you test with that branch?

This is happening when error is added in the page.

base_path() is returning null in render() function of error_page/src/ErrorPageRenderer.php.

Please note this is warning which is visible on frontend on the page.

Steps I followed:
1. I added a syntax error in the code after configuration of module.
2. After this I refreshed the page.
3. Now warning message is visible which is breaking the design due to base_path().