BehaviorEvent requires running game for initialization

[alleew]

The BehaviorEvent class requires a running game to initialize, as seen here in its on create block:

on create
GameStateManager manager
seconds = manager:GetGameDisplay():GetSecondsBetweenFrames()
end

This can cause crashes when using actions like AddBehavior on a Button in a Form. It's maybe not unreasonable for it to crash here, though if it does it could use a better error message. What behavior this ought to have is unclear but the current behavior is probably not it.