Check for null pointer prior to modifying the ref count.
Check for null pointer prior to modifying the ref count.

commontk/CTK,danielknorr/CTK,ddao/CTK,vovythevov/CTK,vovythevov/CTK,msmolens/CTK,jcfr/CTK,msmolens/CTK,mehrtash/CTK,mehrtash/CTK,commontk/CTK,commontk/CTK,151706061/CTK,151706061/CTK,finetjul/CTK,lassoan/CTK,CJGoch/CTK,SINTEFMedtek/CTK,mehrtash/CTK,Sardge/CTK,rkhlebnikov/CTK,Heather/CTK,AndreasFetzer/CTK,AndreasFetzer/CTK,msmolens/CTK,Sardge/CTK,jcfr/CTK,laurennlam/CTK,AndreasFetzer/CTK,151706061/CTK,laurennlam/CTK,jcfr/CTK,lassoan/CTK,danielknorr/CTK,sankhesh/CTK,jcfr/CTK,pieper/CTK,sankhesh/CTK,Heather/CTK,lassoan/CTK,Heather/CTK,Sardge/CTK,pieper/CTK,mehrtash/CTK,msmolens/CTK,SINTEFMedtek/CTK,ddao/CTK,SINTEFMedtek/CTK,vovythevov/CTK,ddao/CTK,sankhesh/CTK,CJGoch/CTK,danielknorr/CTK,naucoin/CTK,151706061/CTK,SINTEFMedtek/CTK,CJGoch/CTK,fedorov/CTK,laurennlam/CTK,espakm/CTK,fedorov/CTK,naucoin/CTK,sankhesh/CTK,naucoin/CTK,finetjul/CTK,pieper/CTK,Heather/CTK,finetjul/CTK,CJGoch/CTK,danielknorr/CTK,pieper/CTK,CJGoch/CTK,espakm/CTK,SINTEFMedtek/CTK,fedorov/CTK,rkhlebnikov/CTK,jcfr/CTK,naucoin/CTK,Sardge/CTK,laurennlam/CTK,151706061/CTK,espakm/CTK,AndreasFetzer/CTK,finetjul/CTK,commontk/CTK,rkhlebnikov/CTK,ddao/CTK,vovythevov/CTK,lassoan/CTK,espakm/CTK,fedorov/CTK,rkhlebnikov/CTK