Fix namespace rule runtime crash (#499)

* Fix `namespace` rule runtime crash

* Don't do `namespace.get()` twice

* Add changelog note

CHANGELOG.md

@@ -4,6 +4,8 @@ This project adheres to [Semantic Versioning](http://semver.org/).
 This change log adheres to standards from [Keep a CHANGELOG](http://keepachangelog.com).
 
 ## [Unreleased]
+### Fixed
+- [`namespace`] exception for get property from `namespace` import, which are re-export from commonjs module ([#416])
 
 ## [1.13.0] - 2016-08-11
 ### Added

src/rules/namespace.js

@@ -131,9 +131,12 @@ exports.create = function namespaceRule(context) {
           break
         }
 
+        const exported = namespace.get(dereference.property.name)
+        if (exported == null) return
+
         // stash and pop
         namepath.push(dereference.property.name)
-        namespace = namespace.get(dereference.property.name).namespace
+        namespace = exported.namespace
         dereference = dereference.parent
       }
 

tests/files/commonjs-namespace/a.js

@@ -0,0 +1 @@
+export { default as b } from './b'

tests/files/commonjs-namespace/b.js

@@ -0,0 +1 @@
+module.exports = {}

tests/src/utils.js

@@ -84,4 +84,8 @@ export const SYNTAX_CASES = [
     code: 'export * from "./issue-370-commonjs-namespace/bar"',
     settings: { 'import/ignore': ['foo'] },
   }),
+
+  test({
+    code: 'import * as a from "./commonjs-namespace/a"; a.b',
+  }),
  ]