Merge branch 'placeatmecrash' into 'master'

Don't crash the game when placing a non-actor

See merge request OpenMW/openmw!443

apps/openmw/mwworld/worldimp.cpp

@@ -1345,7 +1345,11 @@ namespace MWWorld
 
         moveObject(ptr, ptr.getCell(), pos.x(), pos.y(), pos.z());
         if (force) // force physics to use the new position
-            mPhysics->getActor(ptr)->resetPosition();
+        {
+            auto actor = mPhysics->getActor(ptr);
+            if(actor)
+                actor->resetPosition();
+        }
     }
 
     void World::fixPosition()