Absolutely not. Just like every developed country, there is a continuity plan in case of issues. The deputy leader of the party in power is supposedly that person. That the Governor General then appoints that person Prime Minister is an implementation detail.
It's just that in Canada, that continuity plan is reserved for unfortunate deaths. When a PM wants to resign, they basically do what Trudeau did; they announce their party will do a leadership race while they stay on as PM.