fix(auth): Fix for missing exception type for sign in

[gpanshu]

• PR title and description conform to Pull Request guidelines.

Issue #, if available: #2523

Description of changes: UserLambda exception was not present in the converter and instead we were sending an unknown exception back to the customer. This fixes that.

How did you test these changes?
(Please add a line here how the changes were tested)

Documentation update required?

• No
• Yes (Please include a PR link for the documentation update)

General Checklist

• Added Unit Tests
• Added Integration Tests
• Security oriented best practices and standards are followed (e.g. using input sanitization, principle of least privilege, etc)

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.