Permit non-DEV Elements in React.Children w/ DEV (#32117)

packages/react/src/__tests__/ReactChildren-test.js

@@ -1039,6 +1039,31 @@ describe('ReactChildren', () => {
     });
   });
 
+  it('does not throw on children without `_store`', async () => {
+    function ComponentRenderingFlattenedChildren({children}) {
+      return <div>{React.Children.toArray(children)}</div>;
+    }
+
+    const source = <div />;
+    const productionElement = {};
+    Object.entries(source).forEach(([key, value]) => {
+      if (key !== '_owner' && key !== '_store') {
+        productionElement[key] = value;
+      }
+    });
+    Object.freeze(productionElement);
+
+    const container = document.createElement('div');
+    const root = ReactDOMClient.createRoot(container);
+    await act(() => {
+      root.render(
+        <ComponentRenderingFlattenedChildren>
+          {productionElement}
+        </ComponentRenderingFlattenedChildren>,
+      );
+    });
+  });
+
   it('should escape keys', () => {
     const zero = <div key="1" />;
     const one = <div key="1=::=2" />;

packages/react/src/jsx/ReactJSXElement.js

@@ -813,7 +813,9 @@ export function cloneAndReplaceKey(oldElement, newKey) {
   );
   if (__DEV__) {
     // The cloned element should inherit the original element's key validation.
-    clonedElement._store.validated = oldElement._store.validated;
+    if (oldElement._store) {
+      clonedElement._store.validated = oldElement._store.validated;
+    }
   }
   return clonedElement;
 }