Currently in HEAD print_scale_menu_helpbutton() & help_button::make_scale_menu() are throwing exceptions.
print_scale_menu_helpbutton() is in deprecated lib and is simply used as follows:
2 immediate problems are
- OUTPUT doesn't have a help_button method.... it should probably be help_icon
- The help_button class doesn't exist... it should probably be moodle_help_icon
However even after those have been corrected you still get mountains of exceptions because of different things not being set on the classes.
I'm not 100% sure but in this case scale menu is a fringe case as it has a special help page (Am I thinking of the right thing here).
I would imagine that the whole implementation of that needs to be re-thought.
Also to whoever takes on this issue, grap for '::make_scale_menu' there are several implementation that need correcting.