fix(front): hack to hide a bug due to quadtree reduce error.
fix(front): hack to hide a bug due to quadtree reduce error.

The quadtree should not return an empty array of items.
The root cause has to be fixed and found.
This hack avoids errors on front end, and should be removed once root cause is solved

lightstream-company/velomagg,lightstream-company/velomagg