Core/Maps: use correct map pointer to get grids in GetWaterOrGroundLevel

src/server/game/Entities/Object/Object.cpp

@@ -1465,7 +1465,7 @@ bool WorldObject::IsWithinLOS(float ox, float oy, float oz, LineOfSightChecks ch
     return true;
 }
 
-bool WorldObject::IsWithinLOSInMap(const WorldObject* obj, LineOfSightChecks checks, VMAP::ModelIgnoreFlags ignoreFlags) const
+bool WorldObject::IsWithinLOSInMap(WorldObject const* obj, LineOfSightChecks checks, VMAP::ModelIgnoreFlags ignoreFlags) const
 {
     if (!IsInMap(obj))
         return false;