ServiceManager throws NullPointerException in stopServices() method in the line:
   harness.removeObserver(this);
It happens if user cancels test run when the last test of the run has been started already. In this case services are being stopped simultaniously from ServiceManager.stoppingTestRun() and from ServiceManager.finishedTesting(), one of the threads sets "harness" variable to null, then another tries to remove observers.