fix(EventEmitter) throw non func argument facebook#35577 facebook#36087

Author: cedric Madoerin

Libraries/vendor/emitter/EventEmitter.js

@@ -74,6 +74,9 @@ export default class EventEmitter<TEventToArgsMap: {...}>
     listener: (...args: $ElementType<TEventToArgsMap, TEvent>) => mixed,
     context: mixed,
   ): EventSubscription {
+    if (typeof listener !== 'function') {
+      throw new TypeError('EventEmitter.addListener(…): 2nd argument must be a function.');
+    }
     const registrations = allocate<_, _, TEventToArgsMap[TEvent]>(
       this._registry,
       eventType,

Libraries/vendor/emitter/__tests__/EventEmitter-test.js

@@ -78,6 +78,13 @@ describe('listeners', () => {
     expect(results).toEqual(['A', 'B', 'C']);
   });
 
+  it('registers an event with an illegal argument', () => {
+    const emitter = new EventEmitter<{A: []}>();
+    const fakeFunction = ({}: any);
+
+    expect(() => emitter.addListener('A', fakeFunction)).toThrow('EventEmitter.addListener(…): 2nd argument must be a function.');
+  });
+
   it('invokes the same listener registered multiple times', () => {
     const emitter = new EventEmitter<{A: []}>();