fixed seg fault due to null cluster
fixed seg fault due to null cluster

pchrista/AliPhysics,nschmidtALICE/AliPhysics,AMechler/AliPhysics,alisw/AliPhysics,adriansev/AliPhysics,mpuccio/AliPhysics,victor-gonzalez/AliPhysics,victor-gonzalez/AliPhysics,rihanphys/AliPhysics,rbailhac/AliPhysics,nschmidtALICE/AliPhysics,AMechler/AliPhysics,AMechler/AliPhysics,adriansev/AliPhysics,pchrista/AliPhysics,pchrista/AliPhysics,AMechler/AliPhysics,rihanphys/AliPhysics,victor-gonzalez/AliPhysics,victor-gonzalez/AliPhysics,nschmidtALICE/AliPhysics,nschmidtALICE/AliPhysics,adriansev/AliPhysics,pchrista/AliPhysics,alisw/AliPhysics,AMechler/AliPhysics,adriansev/AliPhysics,victor-gonzalez/AliPhysics,rbailhac/AliPhysics,nschmidtALICE/AliPhysics,mpuccio/AliPhysics,mpuccio/AliPhysics,pchrista/AliPhysics,mpuccio/AliPhysics,alisw/AliPhysics,pchrista/AliPhysics,adriansev/AliPhysics,rihanphys/AliPhysics,victor-gonzalez/AliPhysics,rihanphys/AliPhysics,mpuccio/AliPhysics,nschmidtALICE/AliPhysics,nschmidtALICE/AliPhysics,alisw/AliPhysics,rihanphys/AliPhysics,pchrista/AliPhysics,alisw/AliPhysics,rbailhac/AliPhysics,victor-gonzalez/AliPhysics,mpuccio/AliPhysics,rihanphys/AliPhysics,adriansev/AliPhysics,mpuccio/AliPhysics,alisw/AliPhysics,rbailhac/AliPhysics,rbailhac/AliPhysics,rbailhac/AliPhysics,alisw/AliPhysics,rihanphys/AliPhysics,adriansev/AliPhysics,rbailhac/AliPhysics,AMechler/AliPhysics,AMechler/AliPhysics