Improve error handling.

[davidlehn]

• Attempt to improve error handling.
• One goal is to return 400 instead of 500 for some common errors.
• I wasn't sure where to put failure tests. Made a "misc" file that can run a handful of simple tests and check for errors. I think the boilerplate copied from another file could be simplified. Help wanted.
• I'm not sure what this API should do for errors. Should any details be returned to client? There are many possible causes of errors coming from the issuer endpoint code. jsonld lib, vc lib, other libs could fail on input data. What should be exposed? How do we check for errors from libs like vc that only use generic 'Error' or 'TypeError'?

Addresses: #169.

[aljones15]

Approving provided Author feels this is ready.

[aljones15]

@davidlehn this might be something for a subsequent PR, but according to the VC-API this should be returning the verification results in the body of the response. Not sure if this PR is doing that.

[davidlehn]

I was hoping for a bit more discussion here. This does handle one specific jsonld.js error code. But it doesn't handle any others, or any of the generic vc errors, so the first simple tests I wrote still fail. I'm not sure where the line is on exposing more details with cause, or what might need to be filtered out from being returned to clients.

[dlongley]

@davidlehn,

I think we can add better error support incrementally -- just having what you have here is really useful so we should not wait on it.

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 90.76923% with 6 lines in your changes missing coverage. Please review.

Project coverage is 90.72%. Comparing base (c40f64d) to head (356d5fb).

Files	Patch %	Lines
lib/http.js	90.76%	6 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #172      +/-   ##
==========================================
+ Coverage   90.53%   90.72%   +0.19%     
==========================================
  Files          17       17              
  Lines        3170     3235      +65     
==========================================
+ Hits         2870     2935      +65     
  Misses        300      300              

Files	Coverage Δ
lib/http.js	89.88% <90.76%> (+0.50%)	⬆️

... and 2 files with indirect coverage changes

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[davidlehn]

This code got a bit tricky. There are a variety of errors that could be thrown, and it's unclear how dependent other code might be on what this API returns. This is trying to improve it a bit. The bedrock-vc-delivery code has similar work and there is some DRY opportunity here probably by moving some of the common code to a bedrock helper if possible. Suggestions or patches welcome.

[dlongley]

This implementation needs to be updated (it was taken from a source where some bugs were discovered):

https://github.com/digitalbazaar/bedrock-vc-delivery/blob/main/lib/helpers.js#L151-L170

Once that's updated, I think this is ready to go.

[davidlehn]

Aligned more with that code. jsonld.js doc loader is using .details.cause for not found errors, which also need stripping. Not sure if that's an issue in the other library as well.

[dlongley]

I think it's probably fine.