fix(vcr/verifier): handle unparseable issuer DID instead of nil deref

[SAY-5]

Closes #4235

Verify discarded the error from did.ParseDID(credentialToVerify.Issuer.String()) and then dereferenced the resulting (possibly nil) *did.DID at v.didResolver.Resolve(*issuerDID, &metadata), panicking the node when an external issuer emitted a non-RFC3986 did:x509.

Surface the parse error as a regular validation failure ("could not validate issuer: ...") so the request fails cleanly with a 4xx instead of crashing the verifier goroutine.

Added a regression test under TestVerifier_Verify/with_signature_check that wraps the call in require.NotPanics and asserts the error is surfaced. The test panics on master and passes with this change.

[qltysh]

Coverage Impact

⬇️ Merging this pull request will decrease total coverage on master by 0.09%.

Modified Files with Diff Coverage (1)

Rating	File	% Diff	Uncovered Line #s
	vcr/verifier/verifier.go	100.0%
	Total	100.0%

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[reinkrul]

@SAY-5 this repository requires signed commits, I can't merge otherwise

[reinkrul]

Suggested change

	return fmt.Errorf("could not validate issuer: %w", err)
	return fmt.Errorf("could not parse issuer: %w", err)

[reinkrul]

Suggested change

	assert.Contains(t, validationErr.Error(), "could not validate issuer")
	assert.Contains(t, validationErr.Error(), "could not parse issuer")

[SAY-5]

Thanks for the heads up. I'll re-sign the commits with a verified GPG key and force-push the updated branch shortly.

[SAY-5]

Applied both suggestions in c22d536: the parse-error path now reads could not parse issuer and the test asserts on that message. go test ./vcr/verifier/... is green. The commit is SSH-signed but the signing key on this account is not yet registered as a verified signing key on github.com, so GitHub still shows it as unverified. Will get the SSH signing public key added under Settings -> SSH and GPG keys -> Signing key shortly so the verification badge flips on.

[SAY-5]

Applied both suggestions, the parse-path error now says 'could not parse issuer' and the assertion was updated to match. Pushed 2ce91f9.