Possible bug in seafile 12.06 thumbnail generation

Here is the second in my series of possible bugs when upgrading from Seafile 11 to Seafile 12.

When clicking through the web interface and going from directory to directory, there were several that triggered these errors in the logs:

[2024-12-23 14:50:41] [INFO] start to serve on pipe client
2024-12-23 14:50:41,595 [ERROR] seahub.thumbnail.utils:211 pdf_bytes_to_images [Errno 2] No such file or directory: 'pdftoppm'
2024-12-23 14:50:41,597 [ERROR] seahub.thumbnail.utils:239 create_pdf_thumbnails [Errno 2] No such file or directory: '/tmp/c10c889d.png'
2024-12-23 14:50:41,598 [ERROR] django.request:241 log_response Internal Server Error: /thumbnail/1b9b2a8a-22bb-40e5-991d-48b2dfa305ac/create/
Traceback (most recent call last):
  File "/opt/seafile/seafile-server-12.0.6/seahub/seahub/thumbnail/utils.py", line 235, in create_pdf_thumbnails
    ret = _create_thumbnail_common(tmp_path, thumbnail_file, size)
          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/opt/seafile/seafile-server-12.0.6/seahub/seahub/thumbnail/utils.py", line 278, in _create_thumbnail_common
    image = Image.open(fp)
            ^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.12/dist-packages/PIL/Image.py", line 3431, in open
    fp = builtins.open(filename, "rb")
         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
FileNotFoundError: [Errno 2] No such file or directory: '/tmp/c10c889d.png'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/opt/seafile/seafile-server-12.0.6/seahub/thirdpart/django/core/handlers/exception.py", line 55, in inner
    response = get_response(request)
               ^^^^^^^^^^^^^^^^^^^^^
  File "/opt/seafile/seafile-server-12.0.6/seahub/thirdpart/django/core/handlers/base.py", line 197, in _get_response
    response = wrapped_callback(request, *callback_args, **callback_kwargs)
               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/opt/seafile/seafile-server-12.0.6/seahub/seahub/auth/decorators.py", line 69, in _wrapped_view
    return view_func(request, *args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/opt/seafile/seafile-server-12.0.6/seahub/seahub/thumbnail/views.py", line 59, in thumbnail_create
    success, status_code = generate_thumbnail(request, repo_id, size, path)
                           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/opt/seafile/seafile-server-12.0.6/seahub/seahub/thumbnail/utils.py", line 129, in generate_thumbnail
    return create_pdf_thumbnails(repo, file_id, path, size,
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/opt/seafile/seafile-server-12.0.6/seahub/seahub/thumbnail/utils.py", line 240, in create_pdf_thumbnails
    os.unlink(tmp_path)
FileNotFoundError: [Errno 2] No such file or directory: '/tmp/c10c889d.png'