code: function (msg) {
          // restart MutexJs in case exception caused fatal javascript halt
          MutexJs.recover();
  
          // unexpected exception so log in errors and move to next
          var t = PFT.tester.currentTest();
          t.errors.push(msg);
          PFT.tester.onError({ test: t, message: msg });
  
          PFT.tester.closeTest(t);
          // move to next test
          MutexJs.release(t.runUnlockId);
      }
docs: function provides handling for expected exceptions thrown to halt
  the currently running script. typically this will be called from the
  phantom.onError function if tests are running.
   @ignore