The following JSON is an example of an error received when making a request against v2 of the API:

{
    'error_description': 'The provided authorization grant...',
    'error': 'invalid_grant'
}

It would appear that error is a special constant that represents a specific type of error (an invalid authorization code in this case). Is there a list anywhere of all such constants?

For example, what would error be set to if I made a request with an expired access token?