Unable to test run because of "missingno"

when i try to play test, it crashes just when it finishes loading, saying:

Holder{width=16, height=16, name=minecraft:item/white_dye}
Holder{width=16, height=16, name=minecraft:item/wooden_axe}
Holder{width=16, height=16, name=minecraft:item/wooden_hoe}
Holder{width=16, height=16, name=minecraft:item/wooden_pickaxe}
Holder{width=16, height=16, name=minecraft:item/wooden_shovel}
Holder{width=16, height=16, name=minecraft:item/wooden_sword}
Holder{width=16, height=16, name=minecraft:item/writable_book}
Holder{width=16, height=16, name=minecraft:item/written_book}
Holder{width=16, height=16, name=minecraft:item/yellow_dye}
Holder{width=16, height=16, name=minescape:items/tunnen_axe}
Holder{width=16, height=16, name=minescape:items/tunnen_pickaxe}
Holder{width=16, height=16, name=minescape:items/tunnen_shovel}
Holder{width=16, height=16, name=minescape:items/tunnen_sword}
Holder{width=16, height=16, name=minecraft:missingno}
13:57.59 [Worker-Main-5/FATAL] [ne.mi.co.ForgeMod/]: Preparing crash report with UUID 9139a194-9602-4dcd-ba6d-552dda0ad7e5
13:57.59 [Render thread/INFO] [STDOUT/]: [net.minecraft.crash.CrashReport:makeCategoryDepth:227 Negative index in crash report handler (13/15)
13:57.59 [Render thread/FATAL] [ne.mi.co.ForgeMod/]: Preparing crash report with UUID 16bb5873-0ee0-45b7-b3da-c3ef1a602617
13:57.59 [Render thread/FATAL] [minecraft/Minecraft]: Unreported exception thrown!
java.lang.NegativeArraySizeException: null

if anyone needs more info ill paste more of it into replies.