Getting this error message while launching a rocket then it crashes:
The mod Wave Defense Unlimited caused a non-recoverable error.
Please report this error to the mod author.

Error while running event Wave_Defense_Unlimited::on_tick (ID 0)
Wave_Defense_Unlimited/wd-scenario.lua:292: attempt to index field '?' (a nil value)
stack traceback:
Wave_Defense_Unlimited/wd-scenario.lua:292: in function <Wave_Defense_Unlimited/wd-scenario.lua:282>

maybe this could happen when the game was loaded shortly after a rocket launch i guess

It crashes withouts loading, I was just playing. I tested now with an older save and as soon as I launch it, it crashes.

fixed