AHA! This was my culprit! I had reparented everything and made textures unique, nothing was working. 4 errors every save. So, like you said, I went to my node tab, disconnected & then reconnected the "toggle_pressed" signal and BAM, 3 errors! Did it for the other 3 buttons and the 4 errors were gone! Thank you SO much.
*Definitely has to do with the signals messing up when we copy/paste or duplicate.
*wondering if it's when the button WAS the parent, but then isn't anymore when we copy/paste or duplicate, and put into a new parent? I say this because the other people getting this error seemed to have all duplicated something and put in a new scene and that was their error moment. Also noticed we all had a sprite parent when this happened.
Thanks again @Wakatta ...may you get 10,000 Godot Forum points added to your name!