Throw more specific error if passed undefined in React.cloneElement (facebook#12534)

* throw error if passed undefined

* should be TypeError

* simplify

* use invariant

* editor messed up spacing

* better check

* Revert "better check"

This reverts commit 2733707.

* yarn prettier test was failing

* more explicit copy

* es6 import

* tests

* formatting

* Move import

Author: wherestheguac

packages/react/src/ReactElement.js

@@ -5,6 +5,7 @@
  * LICENSE file in the root directory of this source tree.
  */
 
+import invariant from 'fbjs/lib/invariant';
 import warning from 'fbjs/lib/warning';
 import {REACT_ELEMENT_TYPE} from 'shared/ReactSymbols';
 
@@ -290,6 +291,12 @@ export function cloneAndReplaceKey(oldElement, newKey) {
  * See https://reactjs.org/docs/react-api.html#cloneelement
  */
 export function cloneElement(element, config, children) {
+  invariant(
+    !(element === null || element === undefined),
+    'React.cloneElement(...): The argument must be a React element, but you passed %s.',
+    element,
+  );
+
   let propName;
 
   // Original props are copied

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

@@ -359,4 +359,18 @@ describe('ReactElementClone', () => {
     }
     expect(clone.props).toEqual({foo: 'ef'});
   });
+
+  it('throws an error if passed null', () => {
+    const element = null;
+    expect(() => React.cloneElement(element)).toThrow(
+      'React.cloneElement(...): The argument must be a React element, but you passed null.',
+    );
+  });
+
+  it('throws an error if passed undefined', () => {
+    let element;
+    expect(() => React.cloneElement(element)).toThrow(
+      'React.cloneElement(...): The argument must be a React element, but you passed undefined.',
+    );
+  });
 });