Mulligan errors and replace stray messages

[ghost]

Currently the mulligan phase, causes errors, and this results in stray "Replaced" messages, that do not disappear. It seems to be a timing issue, namely that mulligan is triggered before the game is able to handle mulligan. A hacky fix would be a pre-delay.

[ghost]

The issue is an exception from within MulliganManager.ToggleHoldState

[helios-]

I think it's m_UIbuttons that's null. Waiting for that seems to fix it: helios-@c892be0