(Mac OS) Forge Server wont launch with start.command

Hey guys. I've recently been trying to run a modded minecraft server for me and my friend stop on through my mac so that the ram usage wont affect my actual PC. Unfortunately, it has been way more complicated than the youtube videos I've watched suggested it to be. Although I can get the server up and running, the amount of ram that it has it so minuscule that server is basically unplayable. Upon attempting to create a start.command executable to start the server and give it 8 gbs of ram, I run into the error message 

Last login: Wed Nov 11 19:50:57 on ttys001

joemomas-mbp:~ joemoma$ /Users/joemoma/Desktop/RAD-Serverpack-1.40a/start.command ; exit;

A problem occurred running the Server launcher.java.lang.reflect.InvocationTargetException

at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)

at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)

at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)

at java.base/java.lang.reflect.Method.invoke(Method.java:567)

at net.minecraftforge.fml.relauncher.ServerLaunchWrapper.run(ServerLaunchWrapper.java:70)

at net.minecraftforge.fml.relauncher.ServerLaunchWrapper.main(ServerLaunchWrapper.java:34)

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

logout

Saving session...

...copying shared history...

...saving history...truncating history files...

...completed.

[Process completed]

I have tried to search online for the solution but I have no idea what the problem even is! Am I running version 9 of Java? or is there something else that is stopping the command from executing properly?