Hacking Gaming Hardware ROM Hack Trinity Mod Loader help

[VC1]

I am tring to texture mod Pokemon Scarlet. I am currently stuck in the romfs tree view. When I try to save a file, I get the error:

"Unhandled exception has occurred in your application. If you click continue, the application will ignore this error and attempt to continue. If you click quit, the application will close immediately.

Object reference not set to an instance of an object."

I am trying to save it into the new folder I choose for "set output folder" to open it in Toolbox.