From 8e634e18c0f629874b591c26dae01e84ea3fd499 Mon Sep 17 00:00:00 2001
From: somaz <112675579+somaz94@users.noreply.github.com>
Date: Thu, 4 Jun 2026 16:40:54 +0900
Subject: [PATCH] fix: avoid panic when a schema document decodes to null
 (#356)

---
 pkg/validator/validator.go      |  7 +++++++
 pkg/validator/validator_test.go | 34 +++++++++++++++++++++++++++++++++
 2 files changed, 41 insertions(+)

diff --git a/pkg/validator/validator.go b/pkg/validator/validator.go
index 3c9d6f6..13842bc 100644
--- a/pkg/validator/validator.go
+++ b/pkg/validator/validator.go
@@ -372,6 +372,13 @@ func downloadSchema(registries []registry.Registry, l jsonschema.SchemeURLLoader
 	for _, reg := range registries {
 		path, s, err = reg.DownloadSchema(kind, version, k8sVersion)
 		if err == nil {
+			// A schema document that decodes to nil (for example a file whose
+			// entire content is the literal "null") is accepted by AddResource
+			// but makes Compile dereference a nil root and panic. Treat it as a
+			// non-parseable response and try the next registry instead.
+			if s == nil {
+				continue
+			}
 			c := jsonschema.NewCompiler()
 			c.RegisterFormat(&jsonschema.Format{"duration", validateDuration})
 			c.UseLoader(l)
diff --git a/pkg/validator/validator_test.go b/pkg/validator/validator_test.go
index 36a2b3f..8284763 100644
--- a/pkg/validator/validator_test.go
+++ b/pkg/validator/validator_test.go
@@ -460,6 +460,40 @@ interval: test
 			Invalid,
 			[]ValidationError{{Path: "/interval", Msg: "'test' is not valid duration: must start with P"}},
 		},
+		{
+			// A schema file whose entire content is the literal "null" decodes to
+			// a nil document. It used to reach jsonschema's Compile and panic with
+			// a nil pointer dereference (issue #337); it must now be treated as a
+			// missing schema instead.
+			"schema document is null",
+			[]byte(`
+kind: name
+apiVersion: v1
+firstName: foo
+`),
+			[]byte(`null`),
+			nil,
+			true,
+			false,
+			Skipped,
+			[]ValidationError{},
+		},
+		{
+			// Same as above but with IgnoreMissingSchemas disabled: a null schema
+			// document must surface as a graceful Error, not a panic (issue #337).
+			"schema document is null, do not ignore missing",
+			[]byte(`
+kind: name
+apiVersion: v1
+firstName: foo
+`),
+			[]byte(`null`),
+			nil,
+			false,
+			false,
+			Error,
+			[]ValidationError{},
+		},
 	} {
 		val := v{
 			opts: Opts{