Can't say much about the first goal. 2nd goal isn't a mistake by him, just it is something De Gea has made a habit out of saving over the years as he is still incredible with his feet. Its something we have to accept and keep in mind. Henderson might develop into a good goalkeeper, but hes not and won't be De Gea level, or Van der Sar level, or Schmeichel level. 3 legends who stayed for 5+ seasons as the undisputed starter.
Is Henderson that, or is he more a fill in goalkeeper for a few years after De Gea until we get the next guy? I'd lean towards the latter, where he might be solid but I don't think we'll ever feel he is the guy. He's just not really elite with anything and doesn't have stand out elite qualities, whether it is shot stopping, playing with the ball at his feet, handling, reflexes, positioning, saving with his feet, whatever. He is solid at most things, but thats probably it.