It should also be noted that Komarov died in first manned Soyuz spacecraft launched - not the first Soyuz. In other words, Komarov's Soyuz-1 - and naming system isn't obvious in Russian space school - wasn't analogous to Columbia first flight as the very first flight of any STS.
And in Soyuz they also had other pretty close calls. Diving into athmosphere hatch-forward because engine module didn't separate in Shatalov-Volynov-Eliseev-Khrunov group flight... Near premature separation of said engine module in the Intercosmos flight with Afghani cosmonaut... Several ballistic landings - with accelerations up to about 20 g's...
Still nobody died. Perhaps in no small part because of overbuilding the ship and also changing the ship design along its long history, learning on mistakes. Soyuz spacecraft is the real workhorse.
Still, it wouldn't be a "failure" under GP's original definition: "failure" as in "it explodes and everybody dies" :)