AttributeError: 'NoneType' object has no attribute 'split' when downloading a file

[matobaa]

AttributeError occurs when download a file in a zip it has not registered its mimetype

example: COPYING

File "c:/users/matob/onedrive/trac/.venv/lib/site-packages/trac/web/main.py", line 639 , in dispatch_request
File "c:/users/matob/onedrive/trac/.venv/lib/site-packages/trac/web/main.py", line 250 , in dispatch
File "c:/users/matob/onedrive/trac/archiveviewerplugin/1.0/archiveviewer/zip.py", line 309 , in process_request
309	            req.send_header('Content-Type', mime_type)
mime_type	None
File "c:/users/matob/onedrive/trac/.venv/lib/site-packages/trac/web/api.py", line 719 , in send_header
718	        if name.lower() == 'content-type':
719	            self._content_type = value.split(';', 1)[0]
value	None

[matobaa]

In 17508:

ArchiveViewerPlugin: fixes #13612