Better logging for the whole process (such as error message)

[wjlei1990]

As a new user to nnodes, it is very easy to forget to remove root.pickle after an old job failed and to launch a new job. I know root.pickle is supposed a tracking database, but could there be more info provided for the user?

Is there a way to provide better logging (or error message) during the whole process?

Another issue is if nnmk is invoked in a directory without config.toml, then KeyError is invoked. This is not a user-friendly error message.

[icui]

In future versions nnmk will create config.toml interactively if config.toml does not exist.