PDF Embed error

Please see:

Sometimes folks go to Omeka without going through proxy and they encounter the following error:

because the browser URL does not match the baseURL.

Wondering how I could change the error message?

Currently it says:
'Unexpected server response (0) while retrieving PDF.'

I grepped the entire codebase several times with several iterations and no ‘unexpected server response’ lines or derivatives are returned, suggesting that the browser is returning the server based error.

Looks like the error is generated by PDF.js, a JavaScript library for rendering PDFs in the web browser. See: https://mozilla.github.io/pdf.js/

Thank you