DaemonUmbra

If you close those are there any Java processes left?

Are you running anything that uses Java?

Does Get-Process -n Java* report any extra Java processes?

Does typing $Env:JAVA_HOME into Powershell report the same value that you set it to be?

Have you restarted your computer since changing the variable?

After changing the variable did you run .\gradlew --stop and try again?

Don't add Gradle to your path unless it is a standalone installation, the Gradle Wrapper will serve you just fine in most cases.

Oh I'm dumb, drop the \bin for JAVA_HOME...

It appears that you have a program that is preventing Minecraft from taking control of the .\world\chickenchunks\loginTimes.dat file.

Could I get a screenshot of your Environment Variables Panel and your JDK directory?

Did you have any game-related files open in an editor when you tried to run the server?

Have you tried putting double quotes around the path? JAVA_HOME="C:\Program Files\Java\jdk1.8.0_191"

A coremod is a mod made in a certain way that is more intrusive than normal. Most mods allow Forge to do the dirty work but Coremods directly modify Minecraft's code, often in ways that break compatibility with other mods and they tend to not leave a proper trail when things go horribly wrong. As for finding it, it looks like any other mod jar so I'm afraid you just have to look.

What launcher are you using?

May I ask where you are getting your mods?

You have a 1.7.10 coremod installed while trying to run 1.12.2

Have you installed Forge in the past?

Please post your debug.log as described in the logs section of my signature.

Where did you download Forge from, please give a URL.

Please red the logs section of my signature.

Please read up on the StopModReposts project and delete any files you got from that site. Only get Forge from http://files.minecraftforge.net, right now the most reliable place to get mods is from CurseForge.

Where did you get Forge from? Please provide a URL.

Please provide your debug.log using Pastebin or GitHub Gist. (More information in the "logs" section of my signature.)

We do not provide support for versions older than 1.10. Please update to a modern version of Minecraft to receive support.

How are you installing Forge? How are you running Forge?