Module scripts don't load in ViaHTML (affects patterns.hypothes.is)

JavaScript that is loaded as a native ES module via `` fails load in ViaHTML, due to https://github.com/webrecorder/pywb/issues/771.

This issue causes our pattern library to failed to load when proxied: https://via.hypothes.is/https://patterns.hypothes.is/.

The console error includes a messages about variables named "arguments":

<img width="890" alt="Pattern library error" src="https://github.com/hypothesis/viahtml/assets/2458/e0e1517f-9cf4-4230-8a4f-75c7a7ede43c">

This error comes from the JS bundle's preamble after it has been preprocessed by pywb:

<img width="812" alt="Pattern library JS load error" src="https://github.com/hypothesis/viahtml/assets/2458/a4c335e9-a1be-4991-a058-c9cd22b44fe8">