I've been working on Minecraft Forge 1.21 Modding, (I'm a bit inexperienced), and when trying to create my own custom throwable projectile entity, I come across this error I can't seem to fix. The console reads that my "mod not working due to Invalid bare key: '${mod_id}'  ".
Does anyone know why this is happening? The Pastebin link for all the relevant files is https://pastebin.com/h3UaNYwn. Any help would be greatly appreciated. Thanks.

And the mods.toml?

 

Instead of using 

modId="${mod_id}"

try 

modId="wackyweapons"

Even though I defined this in my gradle.properties, it still gives me the same error, even when I change it in my mods.toml, where:
 

Exception in thread "main" java.lang.reflect.InvocationTargetException

...

Caused by: com.electronwill.nightconfig.core.io.ParsingException: Invalid bare key: '${mod_id}'
 

And my mods.toml worked fine before that

Hm, I have no idea

I have no idea which program you use, but in the console, try

grep -r "\${mod_id}" src/main/resources

to find the usages of this key

I use eclipse on windows, but when I use the search tool, it only comes up in mods.toml (I changed it back when it didn't work), and pack.mcmeta

Then it is some kind of issue beyond my programming experience - I have no idea