Digital object file size appears as "NaN undefined" in Firefox

[HaSistrunk]

Describe the bug

In Firefox, the file size for a digital object does not display. Instead of the size, it is displaying it is a not-a-number undefined.

To reproduce

Steps to reproduce the behavior:

1. Navigate to an object with a digital object available to view using the Firefox browser: https://dimes.rockarch.org/objects/SyeUfA7RSXAfpd6uCsCdnM
2. See the details about the object
3. Notice that instead of digital object file size, "NaN undefined" is displayed
4. Compare to Chrome and Safari, which have the file size info available.

Error message or screenshots

[helrond]

This was happening because the content-length header was not part of the response for a HEAD request made in Firefox (but that header was returned in Chrome and Safari). It seems like browsers may implement CORS headers differently. Content-length is supposed to be one of the CORS safelisted response headers but apparently it wasn't part of that list originally, so 🤷

After explicitly setting content-length to be exposed on the resources being requested (PDFs) in AWS S3 this problem was resolved.