The spawn point is set on an arbitrary player once the countdown starts. This does not consider spectators correctly and means that the spawn point could be set at the location of a spectator.

To fix this, only non-spectators should count.
Additionally it would be good to change the hardcoded schedule for when to check for a player and start the game to something that continuously checks if there is a player touching the ground and once there is sets up the spawn point and starts the countdown with a delay of ~1 second.
This should make this procedure a little bit more smooth and should prevent similar issues from happening in the future.