Improve behaviour when contact is not allowed to upload

[Maxime-J]

When a contact who isn't allowed to upload new files tries to upload,
the file is actually sent to the network, the progress is stopped at the end of the transmission and there's finally an error message after some time saying that the file couldn't have been sent to the server.

The upload should be blocked upfront with an error message saying that the contact isn't allowed to upload.

[clochix]

Could you explain in which context a contact could try to upload a file without being allowed?

[Maxime-J]

I create a folder that I share with [email protected] with browse only rights.
With his share link, [email protected] could try (for whatever reason) to drag and drop a file.