Validate derived candidate tags before checks

internal/candidate/check.go

@@ -105,6 +105,9 @@ func Capture(ctx context.Context, request Request) (Candidate, error) {
 	if err := validateNote(note, request.Product, request.Version); err != nil {
 		return captured, fmt.Errorf("release note %q: %w", identity.NotePath, err)
 	}
+	if err := git.CheckTagRef(ctx, repositoryDir, identity.Tag); err != nil {
+		return captured, fmt.Errorf("validate local candidate tag: %w", err)
+	}
 	if exists, err := hasLocalTag(ctx, repositoryDir, identity.Tag); err != nil {
 		return captured, fmt.Errorf("inspect local tag %q: %w", identity.Tag, err)
 	} else if exists {