Nevermind the mod I was trying to add was JEI btw.
For anyone that might see this in the future, I followed this: https://github.com/mezz/JustEnoughItems/wiki/Getting-Started
then I just did gradlew --refresh-dependencies, and it worked like a charm
Question as the title suggests, I already tried adding CodeChickenLib-universal into the mods folder in /run/ but that crashes too...
Is there any way to run compiled mods in a dev environment? Answers much appreciated