Errors when uploading PDFs created from mermaid and markdown

[StephDriver]

Describe the bug Uploading a test PDF which was created from a mix of markdown and mermaid (i.e. contained diagrams) caused an infinite loop on a test-server. Unlikely this would be repeated live, but we should catch the error. In document manager - uploading as manuscript, datafile and production file was fine, but uploading as proofing file caused the loop. When test server was halted and restarted, multiple copies of the file had been added. In galleys - uploading that same file as a galley caused the same behaviour as the proofing file.

Janeway version 1.5.1

To Reproduce Steps to reproduce the behaviour: upload PDF created from markdown and mermaid as a proofing or galley file.

Expected behaviour If such a file should not be uploaded, then an error message should indicate this. If it should be possible to upload, then it should do so without an infinite loop, and only one copy should be uploaded.

Additional context Not known whether the issue is PDF, mermaid, markdown or perhaps any file containing images? Or how many other upload places it would fail. Perhaps a catch for any repeated looping on an upload would be a good preventative for future unexpected files.