Improve error handling

[dtaniwaki]

I found a confusing error message while I was trying to create a new model with the Seldon image. My code raised an exception but the flask app prints an AttributeError first and my error next because my error occurred in the error handling of predict_raw call.

2019-08-14 10:19:22,603 - flask.app:log_exception:1780 - ERROR:  Exception on /predict [POST]
Traceback (most recent call last):
  File "/usr/local/lib/python3.6/site-packages/seldon_core/seldon_methods.py", line 35, in predict
    return user_model.predict_raw(request)
AttributeError: 'MnistClassifier' object has no attribute 'predict_raw'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/usr/local/lib/python3.6/site-packages/flask/app.py", line 2311, in wsgi_app
    response = self.full_dispatch_request()
  File "/usr/local/lib/python3.6/site-packages/flask/app.py", line 1834, in full_dispatch_request
    rv = self.handle_user_exception(e)
  File "/usr/local/lib/python3.6/site-packages/flask_cors/extension.py", line 161, in wrapped_function
    return cors_after_request(app.make_response(f(*args, **kwargs)))
...

Could you consider merging this improvement?

[axsaucedo]

Thank you for the contribution @dtaniwaki, this makes sense! I've added a request to remove the 2nd catch block

[axsaucedo]

No need to catch the exception

[dtaniwaki]

@axsaucedo I updated the code. Please check it again.

[axsaucedo]

Great, thanks @dtaniwaki