Post the code for your Sub isAnyActivityVisible which is where the error is.
I don't have a Sub called isAnyActivityVisible, this is created in the main.java file at compilation.
I think I have sussed the issue as I had previously created a module called vis, which I then removed. On compiling the app, the below code is added to the main.java file. In here is a boolean also called vis, which I think confused the compiler into thinking I was referencing that field instead of a module.
public static boolean isAnyActivityVisible() {
boolean vis = false;
vis = vis | (main.mostCurrent != null);
vis = vis | (information.mostCurrent != null);
vis = vis | (settingsmenu.mostCurrent != null);
vis = vis | (exportdb.mostCurrent != null);
vis = vis | (importdb.mostCurrent != null);
vis = vis | (speechtotext.mostCurrent != null);
vis = vis | (vis.mostCurrent != null);
return vis;}
I had to restore one of the earlier autosaves to get things back to normal, but we're there.
Cheers.