GHSA-7C37-GX6W-8VC5 gitsign --verify panics on empty-certificate PKCS7 and exits 0, bypassing exit-code callers

Summary CertVerifier.Verify in pkg/git/verifier.go unconditionally dereferences certs0 after sd.GetCertificates without checking the slice length. A CMS/PKCS7 signed message with an empty certificate set is a structurally valid DER payload; GetCertificates returns an empty slice with no error,...