[1.19.2] Modifying Vanilla Behavior

[Sunku]

I will start off by getting this right off the table

 

>> The reason I'm doing it is the same reason any modder would want to overwrite or "fix" vanilla stuff <<

 

I simply want to know how to register a block/item over vanilla block item to be used as such.

Ya know, like making grass be sand instead? 
 

I found a post some time ago and honestly I thought it would work but I'm running into issues.

 

Here is my source code:

https://pastebin.com/i71DsTiS

 

The result?

"Caused by: java.lang.RuntimeException: Invalid vanilla replacement. See log for details."

 

So hopefully what I've provided is enough, if not I can provide the whole log as well, but I don't think we'll learn much more?

Thanks in advance!

 

EDIT:

The syntax is a horrid mess because I got frustrated going back and forth with what I thought was correct (obviously wasn't) to just keep getting the same error or my code not ran

Double edit, I am sorry if I come off as rude. I do not mean to

Edited June 13, 2023 by Sunku

[Sunku]

So from more research, my understanding it's just bad to do this with blocks for vanilla in general, but that isn't the same with items is it?