The default view of the attachMany relations, tries to show the preview of the file even for non-image files. For example in the following snapshot, october tries to show preview of the pdf files:
As you can see, the preview fails for pdf files. I need to fix this behavior. How can I override the HTML shown for the uploaded files?

Can you post the fields.yaml config for the form? I guess it includes
Mode
imageis what tells october to create thumbnails