Well this tells you that #add_item
method is being called upon an object that the code expects to be either a toolbar or menu object, but is unexpectedly nil
.
One approach is to add in a conditional guard for all toolbar or menu objects that checks to be sure that they are not nil
or respond_to?(:add_item)
before adding commands or menu procs. When these are detected as nil
then perhaps output an error to inform the user.