keep session alive(not idle) or add session-respawn when expired

[wey-gu]

option 0: send YIELD "foo" to keep the session alive(i.e. by default every 59 minutes)
option 1: catch Session not existed! and do something.

To mitigate this case:

[ERROR (-1002)]: Get sessionId[1667208687399203] failed: Session `1667208687399203' not found: Session not existed!