Improve pat-upload error reporting

[pilz]

Billable to zegg-support

pat-upload can result in errors. The errors are shown in the place where the file has been dropped and vanish quickly after as the object is cleaned away. This is not helpful to report errors.

Find a better way to display and keep visible any errors that might appear.

Way to provoke an error:

• Quaive workspace sidebar, files: Alter the data-pat-upload timeout property to something very small (1) and upload a file.
• pat-upload will terminate and show an error (50x) very briefly and remove it again.
• That error should be visible.