This is a Feature Proposal

Description

When setting environment variables with ${ssm:abcd} variables I was getting the following error message:

 Serverless Warning --------------------------------------

  A valid SSM parameter to satisfy the declaration 'ssm:abcd' could not be found.

When I try to access the variable with the AWS CLI, I get more information:

$ aws ssm get-parameter --name abcd                                                                255 ↵

An error occurred (AccessDeniedException) when calling the GetParameter operation: User: <user info> is not authorized to perform: abcd on resource: <param info>

After adding permissions to the serverless IAM policy, everything started to work as you'd expect.

Adding an error message, either a custom error regarding permissions OR passing through the AWS error would have been super helpful.