Pulp

The Contributing Guide part of the docs needs a new top-level section added to it called "Error Handling". Inside of that page a section on "Errors in Tasks" should also be added about how errors are handled while running a task. The basic things to get across are that:

• Uncaught exceptions are treated as fatal exceptions, the task is marked as failed, and the error representation is returned to the user as the task 'error'.
• Built-In Python exceptions [0] should be used whenever possible.
• Coded exceptions should be used for known error situations. These should link to PulpException
• Non fatal exceptions can be recorded with the append_non_fatal_error() and it should link them to that part of the plugin API docs
• These non-fatal exceptions will be returned with the task details through the API.

[0]: https://docs.python.org/3/library/exceptions.html