Protect against unhandled exception. Fixes #169 (#171)

Author: lukeapage

src/index.js

@@ -78,7 +78,7 @@ function memberExpressionRootIdentifier(path) {
     memberExpression = parent.get('value')
   }
 
-  if (!memberExpression) {
+  if (!memberExpression || memberExpression.type !== 'MemberExpression') {
     // This case is currently unhandled by this plugin.
     return null
   }

test/fixtures/bugfix-169/actual.js

@@ -0,0 +1,7 @@
+class Test extends React.Component {
+    static propTypes = {
+        columns: PropTypes.shape({
+            [constants.TEST]: STRING_PROP_TYPE,
+        }),
+    };
+}

test/fixtures/bugfix-169/expected-remove-es6.js

@@ -0,0 +1 @@
+class Test extends React.Component {}