How to edit a already existing mod or how to make a addon to said mod

[Theatlasteffect]

Ok im trying to make a add a few thing's to a mod that i like but im having a lot of problems setting it up in Intellij i have already goten the mdk from forge for the version that im working on and when i add that in intelli i can launch from inside of it and it works fine but im having problems adding the second mod(main mod) into the project to cuz i think i would need it in the project so the codes could pull from the code from it, or at least i think im still very new to this. after i adding the second mod and do the build it works fine but when i try to run it, it crashes every time and im not sure how to fix it.

crash message: https://pastebin.com/dgisJDQi

[h3tR]

Looking at the log you are either using an unsupported version or have the wrong JDK version installed. I'm not sure what caused the issues with the mixins but if you are using a supported version u won't be able to do anything regardless unless you get the JDK for Java 17.

[ChampionAsh5357]

The version you are using is no longer supported on this forum.

Please update to a modern version of Minecraft to receive support.

Currently supported versions are 1.19.2 (Latest) and 1.18.2 (LTS).