AlliesShareVision game rule floods log with error

[Loobinex]

Start a game with the rule enabled and an active ally and find these log lines in keeperfx.log:

Error: players_are_mutual_allies: Tried to get non-existing player 9!

I investigated and it is because map_block_revealed function receives an ALL_PLAYERS (9). Reproduced it on 1.1 release version, probably been a bug since the introduction of the game rule.

#3571 stops the log, but I do not know if it is the proper fix for the root cause or if it causes more issues.