[BUG] Equality failures due to implicit cast on RequestFailedException.ErrorCode

[Arithmomaniac]

Library name and version

Azure.Storage.Blobs 12.19.1.0

Describe the bug

In several places in the SDK, comparing RequestFailedException.ErrorCode to a strongly typed *ErrorCode type (e.g. BlobErrorCode) can throw an exception.

This is because:

• RequestFailedException.ErrorCode is nullable
• strings can be implicitly converted in == comparisons to *ErrorCode 
• The constructor of *ErrorCode throws if a null is received

This goes against the guideline of

Predefined C# implicit conversions always succeed and never throw an exception. User-defined implicit conversions should behave in that way as well.

Expected behavior

No exception is thrown; in the Reproduction Steps case below, isContainerError is false if inspected.

Actual behavior

An ArgumentNullException is thrown.

Reproduction Steps

try
{
    throw new RequestFailedException(status: 404, message: "Some error.", errorCode: null, innerException: null);
}
catch (RequestFailedException ex)
{
    var isContainerError = ex.ErrorCode == BlobErrorCode.ContainerNotFound;
}

Environment

No response

[github-actions]

Thanks for the feedback! We are routing this to the appropriate team for follow-up. cc @xgithubtriage.

[Arithmomaniac]

Thanks!
What about the non storage APIs? Should I open separate bugs?

[nickliu-msft]

Hi @Arithmomaniac for non-storage APIs, yes please open another GitHub issue without the "Storage" tag and the appropriate team will assist you

[Arithmomaniac]

@nickliu-msft Thanks. I kicked the issue up to the AutoRest repo, which I should have done originally (but thanks for providing the recommended solution 😉)