[Python] No way to handle exceptions in asyncronous code (with callback)

Description

Produced by codegen Python code does not support handling of exceptions in anync mode (with callback). If swagger client code raises exeption, callback will never be called.

Swagger-codegen version

5

Command line used for generation

-l python

Suggest a Fix

Catch all exceptions in generated swagger client and return special type of result in case of exceptions.