[Client] Fix crash for invalid CellRefs in MechanicsHelper::getTarget()

apps/openmw/mwmp/MechanicsHelper.cpp

@@ -112,12 +112,17 @@ mwmp::Target MechanicsHelper::getTarget(const MWWorld::Ptr& ptr)
     {
         MWWorld::CellRef *ptrRef = &ptr.getCellRef();
         
+        if (ptrRef)
+        {
             target.isPlayer = false;
             target.refId = ptrRef->getRefId();
             target.refNumIndex = ptrRef->getRefNum().mIndex;
             target.mpNum = ptrRef->getMpNum();
             target.name = ptr.getClass().getName(ptr);
         }
+        else
+            clearTarget(target);
+    }
 
     return target;
 }