Make it easier to fix missing attachments

As reported here, the error message when double-clicking a missing attachment could be more helpful. Right now it says 'The attached file could not be found' and offers me to 'locate' the file. But it doesn't tell the user where it was looking (e.g. /storage/XAEJ6D7/) — information that is crucial to find the file in a backup. If you're unlucky and you downloaded the PDF from some repository, the Zotero interface won't even tell you the filename (for this reason).

Suggestions:

1. Make the error message for missing attachments more helpful

2. Fix the ever confusing interface issue of filename vs. translator label (thread one, thread two).

This is an old discussion that has not been active in a long time. Instead of commenting here, you should start a new discussion. If you think the content of this discussion is still relevant, you can link to it from your new discussion.