Shard_id=nil timers are now problematic. Before it was quite likely that they were for the current "effective" shard, but now it's possible that the receiving player was in a group when the timer was shared to them, and then they can join some group and get transfered to another shard, and then announce the timer which is known to be to another shard.

Received shard_id=nil timers should get the current known shard_id, or if the shard_id is unknown, then make it un-sharable.

Note that for old versions of WBT this was not an issue, because the timer would not have been sharable while in a group.

Fixed as of 57c525a

Timers without a shard ID (received from another player sharing) can no longer be shared.