`body` in `APIError` is never assigned

[cenhao]

Confirm this is an issue with the Python library and not an underlying OpenAI API

• This is an issue with the Python library

Describe the bug

In the APIError class, there is a body class variable. Based on the comment:

    ""The API response body.

    If the API responded with a valid JSON structure then this property will be the
    decoded result.

    If it isn't a valid JSON structure then this will be the raw response.

    If there was no response associated with this error then it will be `None`.
    """

This class variable should contain the body of the response. However in the __init__ function, the body variable is not assigned and kept.

To Reproduce

Simply error.body will result in:

AttributeError: 'XxxxxxError' object has no attribute 'body'

Code snippets

No response

OS

OS agnostic

Python version

Python version agnostic

Library version

Lib version agnostic

[cenhao]

Also created a PR for this: #949