fix(06-12): reject typed-nil guards and fractional JWT subjects

bouncer/registry_test.go

@@ -233,3 +233,15 @@ func TestJWTGuardRegistryMatchesMiddleware(t *testing.T) {
 		})
 	}
 }
+
+func TestRegisterRejectsTypedNilGuard(t *testing.T) {
+	var reg Registry
+	var g *credPtrGuard
+	if err := reg.Register("p", "n", g); err == nil {
+		t.Fatal("typed-nil guard accepted")
+	}
+}
+
+type credPtrGuard struct{}
+
+func (*credPtrGuard) Authenticate(*http.Request) (*Principal, error) { return nil, nil }