Error in Tutorial

[SwimmingLink]

The fix for when trainers see the player with no Pokémon softlock at 3.1 of https://github.com/pret/pokered/wiki/Fix-No-Mon-Scenarios-Softlock throws an error when making the ROM:
error: home.asm(55) -> home/trainers.asm(140): Unknown symbol "CheckFightingMapTrainers.trainerNotEngaging"
I'm using RGBDS v0.9.1 and I'm near positive I followed that tutorial exactly. I'm not a programmer, so I wouldn't know in the slightest what caused the error.

[Engezerstorung]

The label is conditionned to only be present in the debug rom as such :

IF DEF(_DEBUG)
.trainerNotEngaging
ENDC

Comment out the IF and ENDC for it to work (add a ";" in front of them), or you could delete them outright
The tutorial either missed this step, or the IF condition was added later