Effect Maker: Checking missing assets

If you go through | Edit | Preferences | the "Source Images" shows a list of files but does not show e.g. in red that the file is missing.

As a suggestion adding a feature which would check if the asset exists and in case it doesn't color for the text could be changed to something else than the default (white). This could function in similar manner as the feature in the Qt Creator Resource Editor for example.

Way to reproduce:
1) Build the Effect maker from the sources with Qt 6.4.0
2) Run the Effect Maker
3) Go through | Edit | Preferences | and push ADD button to add some image.
4) Click close
5) Remove/move the image which was added from the directory
6) Go through | Edit | Preferences | and you still see the image listed among "Source Images" without being informed to user that it no longer exists in that path.