Returns 500 on issuance of credentials with undefined Terms or Types

[aljones15]

If a credential is posted to an issuer instance, this library returns 500 if that credential has an undefined term or type.

Example:

{
  '@context': ['...credentials v2 context'],
  'type': ['VerifiableCredential', 'UndefinedType'],
  'credentialSubject': {
    'undefinedTerm': 'notDefinedInContext'
  }

[davidlehn]

• I started adding a test to check this better.
• That data causes the issue endpoint to throw a JsonLdError for a safe mode violation, log it, and rethrow the error, which turns into a ISE/500.
• What should this do? Is there similar code elsewhere on how to nicely capture and expose these sorts of errors? There are other errors that could happen too. I'm not sure what should be exposed and how.

[aljones15]

• I started adding a test to check this better.
• That data causes the issue endpoint to throw a JsonLdError for a safe mode violation, log it, and rethrow the error, which turns into a ISE/500.
• What should this do? Is there similar code elsewhere on how to nicely capture and expose these sorts of errors? There are other errors that could happen too. I'm not sure what should be exposed and how.

I actually don't know, we could look for a jsonld error and then determine the status code from the jsonld error. There was places where we look for bedrock database errors for instance and turn NotFound into a 404.