one logical enhancement in CoreAudio error handler. It should never happen, but so far the only suspect to a rare crash report.

Review URL: http://webrtc-codereview.appspot.com/349002

git-svn-id: http://webrtc.googlecode.com/svn/trunk@1382 4adac7df-926f-26a2-2b94-8c16560cd09d

src/modules/audio_device/main/source/win/audio_device_core_win.cc

@@ -4159,6 +4159,8 @@ Exit:
     RevertCaptureThreadPriority();
 
     if (keepRecording)
+    {
+        if (_ptrClientIn != NULL)
         {
             hr = _ptrClientIn->Stop();
             if (FAILED(hr))
@@ -4170,6 +4172,7 @@ Exit:
             {
                 _TraceCOMError(hr);
             }
+        }
 
         // Trigger callback from module process thread
         _recError = 1;