Provider integration is broken for serverless >2.30.3

[dls314]

The search for error message contents from the provider call at https://github.com/deliveryhero/serverless-aws-documentation/blob/master/src/documentation.js#L107 is broken in serverless > 2.30.3 by the change here serverless/serverless@89b813d

[ottopecz]

The actual error object thrown by the serverless aws provider has changed in the above mentioned versions.

When expecting an error it's better to rely on something more abstract and formal than the message of the error. Good choices might include the code or the statusCode

We published a fix and we plan to maintain the package.
https://www.npmjs.com/package/@kakkuk/serverless-aws-apigateway-documentation