Relic Castle

What does this message mean?
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Pokemon Essentials
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[Pokémon Essentials version 17.1]
Exception: NoMethodError
Message: undefined method `pokedexSeen' for nil:NilClass
PSystem_Utilities:992:in `pbSetViableDexes'
PSystem_Utilities:989:in `each'
PSystem_Utilities:989:in `pbSetViableDexes'
PScreen_PauseMenu:92:in `pbStartPokemonMenu'
Scene_Map:127:in `call_menu'
Scene_Map:213:in `update'
Scene_Map:234:in `main'
Scene_Map:231:in `loop'
Scene_Map:236:in `main'
Main:49:in `mainFunctionDebug'

This exception was logged in
C:\Users\saulu\Saved Games\Pokemon Essentials\errorlog.txt.
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OK
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