Fix crash when propTypes don't have any parent (fixes #182)

Author: yannickcr

lib/rules/prop-types.js

@@ -466,6 +466,7 @@ module.exports = function(context) {
         // ie: ClassX.propTypes.a.b.c = ...
         while (
           propTypes &&
+          propTypes.parent &&
           propTypes.parent.type !== 'AssignmentExpression' &&
           propTypes.property &&
           curDeclaredPropTypes
@@ -480,7 +481,7 @@ module.exports = function(context) {
             propTypes = null;
           }
         }
-        if (propTypes && propTypes.property) {
+        if (propTypes && propTypes.parent && propTypes.property) {
           curDeclaredPropTypes[propTypes.property.name] =
             buildReactDeclarationTypes(propTypes.parent.right);
         }

tests/lib/rules/prop-types.js

@@ -698,6 +698,13 @@ ruleTester.run('prop-types', rule, {
         '};'
       ].join('\n'),
       parser: 'babel-eslint'
+    }, {
+      code: [
+        'const SomeComponent = React.createClass({',
+        '  propTypes: SomeOtherComponent.propTypes',
+        '});'
+      ].join('\n'),
+      parser: 'babel-eslint'
     }
   ],