Can't Run Minecraft Through Eclipse (1.12.2)

[Salticized]

So I wanted to get into modding, and the tutorial I am following has me set up a test version of minecraft to run from eclipse, but it hasn't launched successfully once.

[2021-01-09 20:23:04] [INFO   ] Natives: C:\Users\Jonathan\Downloads\ForgePractice\build\natives 
[2021-01-09 20:23:04] [INFO   ] Main Class: net.minecraft.launchwrapper.Launch 
[2021-01-09 20:23:04] [INFO   ] Srg2Mcp: C:\Users\Jonathan\Downloads\ForgePractice\build\createSrgToMcp\output.srg 
[2021-01-09 20:23:04] [INFO   ] Extra: [] 
[2021-01-09 20:23:04] [INFO   ] Running with arguments: [--version, 1.12, --assetIndex, 1.12, --assetsDir, C:\Users\Jonathan\.gradle\caches\forge_gradle\assets, --accessToken, {REDACTED}, --userProperties, [], --tweakClass, net.minecraftforge.fml.common.launcher.FMLTweaker] 
Exception in thread "main" java.lang.reflect.InvocationTargetException
    at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:64)
    at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.base/java.lang.reflect.Method.invoke(Method.java:564)
    at net.minecraftforge.legacydev.Main.start(Main.java:86)
    at net.minecraftforge.legacydev.MainClient.main(MainClient.java:29)
Caused by: java.lang.ClassCastException: class jdk.internal.loader.ClassLoaders$AppClassLoader cannot be cast to class java.net.URLClassLoader (jdk.internal.loader.ClassLoaders$AppClassLoader and java.net.URLClassLoader are in module java.base of loader 'bootstrap')
    at net.minecraft.launchwrapper.Launch.<init>(Launch.java:34)
    at net.minecraft.launchwrapper.Launch.main(Launch.java:28)
    ... 6 more

this is the crash report I receive in the console.

This is the link to the tutorial I'm using: https://codakid.com/guide-to-minecraft-modding-with-java/

If you need any other info on this to help me out, that would be great!