I know this is a old post but for me with the widget giving the error, I found it to be that I had a variable in the widget and a non-variable widget element with the same name. I renamed the non-variable widget element and then all the variable references become a pointer to the non-variable widget element. I replaced those with the actual variable, and the warning went away. Didn’t even realize that I did that, and I didn’t suspect that a named non-variable widget element would be accessed as a variable.
My Element was a Canvas panel named ‘Tombstone’, and the variable was also named ‘Tombstone’.
So that might be worth checking out a well if its a widget compile warning your getting this on.