Stay close to your goal as much as possible is just a basic rule for all GKs
Ederson's just a very rash GK,even he rushes out he rarely makes himself big,split second late in reacting and these moments of madness are starting to become a recurring theme
For the first goal,yes Laporte gets done by Kane's movement and vacates his space at first but with Cancelo covering,
Son would have had to produce one heck of a finish with him going away from goal and if he scores,fair enough but still
The second goal,same scenario,he rushes out,vacates his space and just opens up the goal,again,with his legs apart
Son would have scored a third too had he had a better touch
He's lucky enough that De Gea and Kepa have been worse and made more errors in the last 18 months or so,otherwise the spotlight would have been on him more because for all his praised 'abililty' on the ball,he just doesn't give us enough of a chance in games when needed as he should for a keeper at a top club.