Error is not raised if any of the approval request fail to send

[marshall7m]

Within the approval request Lambda Function, the function doesn't raise an exception if any of the approval requests fail to send via AWS SES. Currently, the function just returns a status code 500 with a count of failed sends and quietly passes the error return value within the execution but doesn't bring it to the user's attention via any downstream states. With the error passed as a return value, this doesn't allow for exception catching within the Step Function definition to possibly notify the user's that they should update any invalid approval voter email addresses.