Non existing files throw error 500: the thumbnail configuration could not be found

[medienbaecker]

Description

Non-existing files trigger an error 500. I can reproduce this in any installation, also on getkirby.com:

https://getkirby.com/media/site/hello/error.pdf
https://getkirby.com/media/pages/features/hello/error.jpeg

Enabling debug modes shows this error message: The thumbnail configuration could not be found.

Expected behavior
A 404 should be returned instead.

Your setup

Kirby Version
4.2.0