Description of the need In rich text editor in image details, users are allowed to click the insert or update button even if they do not have a file chosen.
Proposed solution You could block the "Update" button until an image is added or have a popup to notify the user that they do not have an image selected when clicking insert/update.
Additional information
Inserting an non-existent file:

Updating after a file is removed:

Recent comments
Ah, got it. You are right, this is a bug. I just opened a bug report: https://github.com/backdrop/backdrop-issues/issues/7238 Hopefully, this will be addressed soon. Thanks for...
Files uploaded using add file
I think, you are misunderstanding what i said. 1.admin/structure/file-types/settings = field/uploaded (or anything else) 2.admin/content/files (Manage Files), (the +Add files) link,...
Files uploaded using add file
The setting on admin/structure/file-types/settings is only for files uploaded via Content > Manage files. Not for files uploaded via a file field. File fields have their own setting for...
Files uploaded using add file