Number of fails on a mission can be reported as "Undefined" if 5 players throw a fail.

[UnknownOrange314]

If there are 4 players on a mission, and one player uses Excalibur on the person who threw a success, then the game will report that an undefined number of fails have been thrown.

https://github.com/cashto/resistance/blob/118c283ba5c9dac9154e2a1181474fdbc765e2a3/server/Game.coffee#L666