Add support for errors.As

[arjantop]

It would be nice if this linter could also detect issues with asserting errors to specific types, this is common in AWS sdk (as well as many places): https://docs.aws.amazon.com/sdk-for-go/v1/developer-guide/handling-errors.html

if awsErr, ok := err.(awserr.Error); ok {

[onokonem]

sorry for the delay, was extrimely busy.

will take a look in the nearest future