add null check for review state object check

Signed-off-by: Stephen Glass <stephen@stephen.glass>

.changeset/slow-ligers-drum.md

@@ -0,0 +1,5 @@
+---
+'@backstage/plugin-scaffolder-react': patch
+---
+
+Fix null check in `isJsonObject` utility function for scaffolder review state component

plugins/scaffolder-react/src/next/components/ReviewState/util.test.ts

@@ -1,5 +1,5 @@
 /*
- * Copyright 2022 The Backstage Authors
+ * Copyright 2024 The Backstage Authors
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -33,6 +33,10 @@ describe('isJsonObject', () => {
     expect(isJsonObject(true)).toBe(false);
     expect(isJsonObject(undefined)).toBe(false);
   });
+
+  it('should return false for null values', () => {
+    expect(isJsonObject(null)).toBe(false);
+  });
 });
 
 describe('getLastKey', () => {

plugins/scaffolder-react/src/next/components/ReviewState/util.ts

@@ -1,5 +1,5 @@
 /*
- * Copyright 2022 The Backstage Authors
+ * Copyright 2024 The Backstage Authors
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -17,7 +17,7 @@
 import { JsonObject, JsonValue } from '@backstage/types';
 
 export function isJsonObject(value?: JsonValue): value is JsonObject {
-  return typeof value === 'object' && !Array.isArray(value);
+  return typeof value === 'object' && value !== null && !Array.isArray(value);
 }
 
 // Helper function to get the last part of the key