main_task/other_task pattern still incorrect

[iceboy233]

if other_task throws an exception, but the parent coroutine is waiting for main_task, it deadlocks.

[iceboy233]

this has caused an out of service now...

[iceboy233]

main_task was introduced so that even if others_task fails, we still wait for the program to complete; however we need to kill the main program in such cases.