... after each successful read().
I completely missed this declaration after a statement during the review
of !13 even though I saw another similar issue!

Also let's reset the error counter to 0 each time a successful read()
happens so that we can continue reading even if a lot of EINTR were to
happen, as long as we globally go forward. Only consecutive errors
increment the counter.

Finally add a small comment to explain why we let EINTR pass instead of
breaking directly.