This is why it is best that a runner leaves one click available til after a run. The rules say that if the runner's hand is less than zero at the end of his turn, he is flatlined. But, if a runner keeps a click available for a run, if he is damaged, he can then spend the click to draw a card so that he is no longer at less than zero. At least I'm pretty sure this would work.
The actual rules quote:
If the Runner takes more damage than the number of cards in
his grip, or if he has a maximum hand size of less than zero at
the end of his turn, then he is flatlined and the Corporation
wins the game.
Two distinct clauses.
If the Runner needs to discard and cannot, the Runner loses.
If the Runner has a hand size lower than zero at end of turn the Runner cannot maintain '0' cards in hand and loses.