Forest start_process fails to restart auxin on Auxin crash

[iamalwaysuncomfortable]

Sometimes auxin crashes crash forest bot. The following Auxin in 0.1.8 crash ended up crashing forest core. #Auxin 0.

Guess is that when auxin fails, the following assert causes start_process to fail https://github.com/mobilecoinofficial/forest/blob/4f8bc65d0c1f49634579ef77403f282a373609f0/forest/core.py#L138

And then because the task is stored within the class dict, no error is sent because the task is never garbage collected. https://github.com/mobilecoinofficial/forest/blob/4f8bc65d0c1f49634579ef77403f282a373609f0/forest/core.py#L534-L536

We should

1. Not use assert for stdin monitoring (asserts are for values always expected to be true, shouldn't be used on values likely to change), we should explicitly check its status and if we detect stderr, restart auxin
2. Monitor the start_process() task and if it is in error state, dereference and start a new task.

[iamalwaysuncomfortable]

https://github.com/mobilecoinofficial/forest/pull/99 <- This pull is the proposed fix

[iamalwaysuncomfortable]

This issue has been mostly solved by:

• Fixing Auxin Crashes
• Implementing Logging of Start_Process