Danebi

You probably don't. Make your own thread and post logs.

Run jarfix.

Oh, sorry. I think I've mistaken your thread with another. Since you have a problem with the installer post the installer log. You can find it in the same folder as the installer.

Another class.

Probably not. Make your own thread and post the complete debug.log.

It's in your logs folder.

Try to run jarfix.

Post the debug.log.

Post the debug.log.

Try to use the srg names.

It's the same, just with the macbook terminal.

https://www.youtube.com/watch?v=j6uMF-PjGT4&ab_channel=LexManos

Post the debug.log.

Try to remove this file: C:\Users\liamr\AppData\Roaming\.minecraft\config\fml.toml

Do you know Java?

Post the debug.log.

Again, post the whole debug.log.

Gist Github.

Post the debug.log.

Why "examplemod"? Probably in the mod annotation you used the id "testingmodd" but in the mods.toml you add an extra "d".

Your mods.toml is probably invalid.

This is not a good tutorial. It doesn't teach you how to mod as it just gives you code to copy and paste. As for your problem...