fix: resolve undefined types to undefined, fixes #1324

Author: theKashey

src/reconciler/resolver.js

@@ -68,5 +68,12 @@ export function resolveNotComponent(type) {
 
 export const resolveSimpleType = type => resolveProxy(type) || resolveUtility(type) || type;
 
-export const resolveType = (type, options = {}) =>
-  resolveProxy(type) || resolveUtility(type) || resolveNotComponent(type) || resolveComponent(type, options) || type;
+export const resolveType = (type, options = {}) => {
+  if (!type) {
+    return type;
+  }
+
+  return (
+    resolveProxy(type) || resolveUtility(type) || resolveNotComponent(type) || resolveComponent(type, options) || type
+  );
+};

test/reactHotLoader.test.js

@@ -47,6 +47,13 @@ describe('reactHotLoader', () => {
         const DivProxy = OriginalReactMock.createElement.mock.calls[0][0];
         expect(DivProxy[PROXY_KEY]).toBeDefined();
       });
+
+      it('null case', () => {
+        reactHotLoader.patch(ReactMock);
+        const result = React.createElement(undefined);
+
+        expect(result.type).toBeUndefined();
+      });
     });
 
     describe('#createFactory', () => {