I'd say Oblak is the only one who's relatively free from mistakes from what I've seen. all of de Gea, Courtois, Ter Stegen, Alisson in the past few years have their share of silly goals let in. hard to say about Ederson, I've hardly watched City or Brazil at all.
out of interest, tried to youtube Oblak mistakes and first page has more FM/FIFA Oblak mistakes than real life lol. I guess this ones the only significant one when Pato was still playing in Europe
As much as I like Buffon, no Szczesny should retain the number 1 jersey. No sentiment. No one is bigger than the club. Buffon should know this better than anyone else; Buffon is on borrowed time anyway (as a GK).