Undefined variable in custom menu procedure causes menu bar aberration

I can replicate this on two different machines, so I definitely believe it’s a bug. If I run a custom menu procedure containing an undefined variable, like ProcList in:

filemenubar "all",
    menu("A1") +
        menuitem("A2","code",{message "Hello World"}) +
        arraymenuitems(ProcList,"code",{message "Hello Jim})

no error message appears but if I then open any procedure in the database, the data sheet adopts the procedure menu bar, as in:


and the database has to be closed to be useable.

Not a big deal but a bug nevertheless.