fix: handle relative and invalid URLs in redirects when passing URL to loadImage()

[lostfictions]

Fixes #865, see the description of the original issue there.

This PR does two things:

• One, this wraps the http.get()/https.get() callback in loadImage() in a try...catch block so that exceptions are properly handled and passed to callers instead of crashing the Node process.

• Two, this passes url.origin as the second parameter to new URL() to ensure that "relative" redirects (where the location header is something like /some/resource.jpg instead of https://site.com/some/resource.jpg) do not cause the constructor to throw an exception.

  Redirects to another domain (for example, a location header to https://other.com from the origin https://site.com) are not affected by adding the second parameter. Only relative URLs are affected -- the kind that currently cause crashes in user code.

Without this fix, passing URLs to loadImage() does not reliably work when the URL has a redirect, and will instead crash the Node process without a full stack trace, even if the call to loadImage() is in a try block.

[lostfictions]

The CI failure seems unrelated. I've also added more details to the PR description. @Brooooooklyn, do you have any feedback?