[Error] Error and crash when generating Pokemon Battle Tower teams. What does it mean?

[SuperSpyroDragon64]

The game crashed with this error message when I walked to the battle tower and told it to generate new battlers. What does this mean?

[Pokémon Essentials version 20.1]
[v20.1 Hotfixes 1.0.7]

Script error in event 3 (coords 2,3), map 55 (Battle Frontier)
Exception: SystemStackError
Message: stack level too deep

***Full script:
pbBattleChallenge.set(
  "towersingle",
  7,
  pbBattleTowerRules(false, false)
)

Backtrace:
015:Validation:18:in `any?'
015:Validation:18:in `block in validate'
015:Validation:16:in `each'
015:Validation:16:in `map'
015:Validation:16:in `validate'
103:GameData:92:in `get'
132:Species:286:in `get_baby_species'
132:Species:286:in `get_baby_species'
132:Species:286:in `get_baby_species'
132:Species:286:in `get_baby_species'