What did I do wrong?

[SamdeMan123124]

I was making my game, but I added a new tileset, and a few new scripts. Which of these resulted in this error message, and how do I fix it?
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Pokemon Essentials
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[Pokémon Essentials version 18.1]

Exception: NoMethodError

Message: undefined method `*' for nil:NilClass



Backtrace:

Tilemap_XP:413:in `addTile'

Tilemap_XP:845:in `refresh'

Tilemap_XP:842:in `each'

Tilemap_XP:842:in `refresh'

Tilemap_XP:941:in `update'

TilemapLoader:49:in `update'

Spriteset_Map:130:in `_animationSprite_update'

Sprite_AnimationSprite:89:in `update'

Spriteset_Map:68:in `_animationSprite_initialize'

Sprite_AnimationSprite:50:in `shadow_initialize'



This exception was logged in

C:\Users\USERNAME\Saved Games\Pokemon Essentials\errorlog.txt.

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OK
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[NettoHikari]

You made a map with one tileset, then switched the map's tileset to a shorter one, which means that any tiles that were near the bottom of the original tileset that you put on this map now can't be found. To fix it, simply install and run the script here: (broken link removed).