Unknown Error when d&d folders into filedrop

[Svanvith]

Initial Checklist

• I understand this is a bug report and questions should be posted in the Community Discussions
• I searched issues and couldn’t find anything (or linked relevant results below)

Bug Description

When you upload folders with subfolder per drag and drop in file drop links, the folders produce "unkown error" messages

Reproduction Steps

• create a file drop link
• open it an inkognito tab
• upload per drag and drop a folder with subfolders

Expected Outcome

Files will be uploaded and folders are ignored.
When we have an errormessage about the folders it should be something like "folders cannot be uploaded in file drops"

Actual Outcome

The subfolder here was named "1"

The unkown error messages can confuse users and we need please better error messages.