crash bug (minecraft 1.12.2)

[wdaewWSREG]

happened when setting the level though NBT to "999999999"

possible fix: set level to Max-level when Level is greater then Max-level.

I know the obligatory messages of "should not of done that" is coming my way but I did it anyways.
also when editing the NBT of a item, when a level-up happens it overrides the values I set for the items.

here's the error it though at me when i did change the level:

Exception caught during firing event net.minecraftforge.event.entity.player.ItemTooltipEvent@43262c17:
java.lang.StackOverflowError
at slimeknights.toolleveling.ModToolLeveling.getXpForLevelup(ModToolLeveling.java:202)
Note: (line was repeated 500+ times)