title: Angular karma phantom before each hook error
body: <p>I am running my tests with karma and phantom, i am using mocha and sinon and sometimes the tests pass and sometimes without any reason i get this errors:</p>
  
  <pre><code>    ✖ "before each" hook: workFn
        ✔ should call get user api
    ✖ "after each" hook for "should call get user api"
  
  Finished in 1.04 secs / 0.2 secs
  
  SUMMARY:
  ✔ 42 tests completed
  ✖ 3 tests failed
  
  FAILED TESTS:
    UserService
      ✖ "before each" hook: workFn
        PhantomJS 1.9.8 (Mac OS X 0.0.0)
      TypeError: 'null' is not an object (evaluating 'document.querySelector('.arrow' + index).classList') (public/client/build/main.js:3195)
  
    ✖ "after each" hook for "should call get user api"
      PhantomJS 1.9.8 (Mac OS X 0.0.0)
      PhantomJS 1.9.8 (Mac OS X 0.0.0)
    TypeError: 'null' is not an object (evaluating 'currentSpec.$injector')
        at public/vendor/angular-mocks/angular-mocks.js:2229
  </code></pre>
  
  <p>What can cause to this problem?</p>