I can see why you think it was not in error, but it is important to understand just how egotistical the Roman See is, and then you will see in this statement more arrogance than condemnation. In saying "There is but one universal Church of the faithful, outside of which no one at all can be saved." what I understand the Catholic church to have been saying is that they see themselves as instrumental in anyone's salvation who is saved. They are not saying, as many have inferred, that people such as the Greek Orthodox cannot be saved since they are not Catholic, they are saying that if they are saved it is because the Catholic church exists. The same would apply to protestants that they see as being outside of the one true church, yet still saved by the work of Christ and the continued presence of the Catholic church. The same would hold for anyone else as well.
But more importantly, do you see that as regards the Quranic verse you provided eariler:
Whether one accepts your interpretation of Catholic theology (wherein only Catholics are saved) or accepts my interpretation of Catholic theology (wheren in any and all who might be saved is up to God, but is possible only because of the Catholic church's existence), that in neither context would they say what the Quran claims would be said.