I wouldn't describe it, I don't think, as a constitutional requirement per se, but if Canada as a state enters into an agreement in international law and agrees to ratify a treaty, it would presume on the supremacy of Parliament to do that if it required legislation. Canada would not ratify a treaty before the necessary criminal offences—in this case—that we're required to adopt are in place. It would presume on Parliament.
I'm not sure that I would describe that as a constitutional problem. It almost would be more of an international law problem, in the sense that Canada would not be in conformity with its legal obligations under the treaty if Parliament then decided not to enact the legislation necessary to complete the implementation package—if that answers the question.