https://gist.github.com/mmmilord/63267ee3953444aa63c7b2142cd3b8e5

DynamicTrees-1.12.2-0.9.6.jar
DynamicTreesPHC-1.12.2-1.4.2.jar

The crash is caused by the Spark Hammers mod. Specifically here
The mod clearly means to use "p" instead of "pos" in the while loop check. Looks like a typo.