Protect against missing prop type

Author: markalfred

src/main.js

@@ -24,6 +24,7 @@ const wrapPropTypes = () => {
   const original = _.cloneDeep(PropTypes)
 
   _.each(_.keys(GENERATORS), (k) => {
+    if (PropTypes[k] === undefined) return
     if (PropTypes[k].isRequired !== undefined) {
       // Simple type. Just extend the object
       PropTypes[k] = addHiddenProperties(PropTypes[k], 'type', k)

test/main.js

@@ -176,6 +176,8 @@ describe('generateProps (correct)', () => {
 
   describe('given a required symbol', () => {
     it('generates a symbol', () => {
+      if (PropTypes.symbol === undefined) return
+
       const propTypes = { mySymbol: PropTypes.symbol.isRequired }
       ComponentAsClass.propTypes = propTypes
       ComponentAsFunction.propTypes = propTypes