Equipment Model Deactivation is Broken

[esoterik]

Attempting to deactivate an equipment model currently gives the following error:

undefined method `equipmentmodels_requirements' for #EquipmentModel:0x005556a1f5dd70 Did you mean? equipment_model_equipment_items_url

...with the following related source:

    # Deactivate the model you had originally intended to deactivate
    @items_class2.destroy
    flash[:notice] = 'Successfully deactivated '\
                   + params[:controller].singularize.titleize\
                   + '. Any related equipment has been deactivated as well.'

The line throwing the exception is @items_class2.destroy.