Something is wrong when bot can choose between pon and kan

[daycheat]

bot is west player

1. 4m|0m444556p|111z678s|||222m666p|256z9s1p7z1m8p|9m326z87p9m|4z92p9m7p6z2p|19s74m1p6s7p|0,0,0,0|3|1|40 (east player's turn)
2. 4m|0m444556p|111z678s|||222m666p|256z9s1p7z1m8p|9m326z87p9m|4z92p9m7p6z24p|19s74m1p6s7p|0,0,0,0|3|1|40 (east player discarded 4p)
3. 4m|0m4556p|111z678s444p|||222m666p|256z9s1p7z1m8p|9m326z87p9m|4z92p9m7p6z2p|19s74m1p6s7p|0,0,0,0|3|1|40 (bot called pon for 4p, even though bot could choose kan)

bot stopped working after called pon for 4p (probably bot couldn't discard a 4p left because of the rule)

[Jimboom7]

Thank you for the detailed debug log, it helped a lot in recreating the situation.
The problem was not being unable to discard the 4p (the bot already makes sure not to do that). But a while ago I changed the way the operations (pon, kan, etc.) are handled: The UI and timer now get closed after accepting the first operation, but unfortunately that also clears the variable that stores the possible operations and causes a nullpointer if there are multiple. I'll push a fix now.