[hotfix] Fixes the spacecube runtime at server start

The problem was checking for index 7 in an array of length 6 (_final_connected_zones_).

Problem solved by using (as intended ?) an associative list instead of the _z_level_ directly as an index.

Edit : will have to be another PR but #4903 is caused by the location being changed without calling _Entered_ for the new loc.