TODO: Improve exception exceptions for model loading/saving

[s0nicboOm]

This is the doc which captures different types of exceptions seen and to be handled in a better way in the upcoming releases:

1. cannot unpack non-iterable int object

Traceback (most recent call last):

  File "/usr/local/lib/python3.10/threading.py", line 973, in _bootstrap
    self._bootstrap_inner()
  File "/usr/local/lib/python3.10/threading.py", line 1016, in _bootstrap_inner
    self.run()
  File "/usr/local/lib/python3.10/threading.py", line 953, in run
    self._target(*self._args, **self._kwargs)
  File "/usr/local/lib/python3.10/concurrent/futures/thread.py", line 83, in _worker
    work_item.run()
  File "/usr/local/lib/python3.10/concurrent/futures/thread.py", line 58, in run
    result = self.fn(*self.args, **self.kwargs)
  File "/opt/pysetup/.venv/lib/python3.10/site-packages/grpc/_server.py", line 625, in _unary_response_in_pool
    response, proceed = _call_behavior(rpc_event, state, behavior,
  File "/opt/pysetup/.venv/lib/python3.10/site-packages/grpc/_server.py", line 494, in _call_behavior
    response_or_iterator = behavior(argument, context)
> File "/opt/pysetup/.venv/lib/python3.10/site-packages/pynumaflow/function/server.py", line 127, in MapFn
    msgs = self.__map_handler(
  File "/app/numaprom/tools.py", line 67, in inner_function
    for vertex, json_data in data:
TypeError: cannot unpack non-iterable int object