It first occurs at 25:14, when a chomper is launched out into space. The error is: RegisterShipNavigation: No free slots in nav_ships. Considering that all of the slots underneath the map for ship dummies were full, I'm assuming that more space is required. Things only continue to get worse from there when we attempt to launch a mine layer.
In short, I think you need to add another 20 lines in order to compensate for the fact there could potentially be 32 small ships in space at a time. (12 players, and 20 AIs since the team limit to AIs appears to be 10.)