[Fix] no-unused-prop-types: avoid a crash

Fixes jsx-eslint#2131.

Author: ljharb

lib/util/propWrapper.js

@@ -8,6 +8,9 @@ function getPropWrapperFunctions(context) {
 }
 
 function isPropWrapperFunction(context, name) {
+  if (typeof name !== 'string') {
+    return false;
+  }
   const propWrapperFunctions = getPropWrapperFunctions(context);
   const splitName = name.split('.');
   return Array.from(propWrapperFunctions).some(func => {

tests/lib/rules/no-unused-prop-types.js

@@ -2975,6 +2975,17 @@ ruleTester.run('no-unused-prop-types', rule, {
         }
       `,
       parser: 'babel-eslint'
+    },
+    {
+      code: `
+        export default class Foo extends React.Component {
+          render() {
+            return null;
+          }
+        }
+
+        Foo.defaultProps = Object.assign({});
+      `
     }
   ],