launchpad.createLaunchpad() enforces buyAmount defined && >0 even if createOnly = true

[bloom-alex]

Hello!

The createLaunchPad method throws if you pass buyAmount = 0 even if createOnly is set to true.

IMO ideally, the input typing would not even allow passing a buyAmount at all if createOnly is true. It would be very obvious to users which parameters are expected in which case.

But at least, it would be cleaner to allow setting 0 or null/undefined.

Same would go for other parameters that are only used to setup the buy transaction (e.g. slippage)