Fix NPE where data.Error is undefined from a 400 response

[mjgp2]

Description

Sometimes (seemingly on a 400 response) the Error is undefined, and data.Error.Code throws a NPE.

Testing

Existing tests should suffice.

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[kuhe]

Thanks for your PR. I believe this needs a corresponding change in the 🪀 🐶 code that generates the code, as seen in what #3085 is getting at.

There is no clear indication at the moment that you are editing generated code, but there is a PR open to change that: smithy-lang/smithy-typescript#538.

[AllanZhengYP]

Hi @mjgp2 Can you also share the content of data when error code cannot be parsed? It'll be helpful to use to roll out a correct fix.

[eliran]

We are hitting the same and similar issues. The proposed fix is only partial.

This is a sample of SQS 400 error (for a DeleteMessage with an invalid receipt):

Errors: {
    Error: {
      Code: 'ReceiptHandleIsInvalid',
      Message: 'The input receipt handle is invalid.'
    }
  },
  RequestId: 'PFS6BZ1KB4DNYC9BQ0N6MWQHX0XKVKTSQZRJ9WXSK6WC9AK0CPOS'

Error is wrapped inside Errors which means code isn't found and we get back a type error rather than a sensible actionable error.

Some 400s return correctly like this one (for SendMessage with large message):

{
  xmlns: 'http://queue.amazonaws.com/doc/2012-11-05/',
  Error: {
    Type: 'Sender',
    Code: 'InvalidParameterValue',
    Message: 'One or more parameters are invalid. Reason: Message must be shorter than 262144 bytes.',
    Detail: ''
  },
  RequestId: 'OLBR5M8PNYFNXHL20G90AINDLBABVK8GNINGS03SLDEIJYG3G42U'
}

I have also seen errors return without Error property at all but I don't have a current example.

This does cause us some issues with migrating from v2 to v3 which handled these errors properly.

[Tetramputechture]

@mjgp2 did you have any updates on this? i am running into this and its obfuscating a small percentage of our API errors, preventing us from knowing what's actually going on. specifically, around 1/100000 calls to SNS PublishMessage when publishing to a push notification (APNS / GCM) endpoint are failing with this NPE. Specifically

Failed to execute PublishMessage command: Cannot read properties of undefined (reading 'Code')

[kuhe]

This was replicated in #4367

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