Errors not written to stderr

[colinbjohnson]

Description of Issue

errors that prevent file copy operations when running aws s3 commands are written to stdout

Steps to Reproduce

tested with both invalid s3 credentials and with destination files that could not be written to)

1. Modify credentials to be invalid (example: export AWS_ACCESS_KEY=xxxxxxxxxxxxxxxxxxx)
2. Run command, with output piped to stdout, example: aws s3 sync s3://mybucket/myobjects/ /Temp > /dev/null

Expected Output

(venv)hostname:Temp username$ aws s3 sync aws s3 sync s3://mybucket/myobjects/ /Temp > /dev/null A client error (InvalidAccessKeyId) occurred when calling the ListObjects operation: The AWS Access Key Id you provided does not exist in our records. Completed 1 part(s) with ... file(s) remaining

Actual Output

(venv)hostname:Temp username$ aws s3 sync aws s3 sync s3://mybucket/myobjects/ /Temp > /dev/null

The same behavior occurs when running in --quiet mode - although the expectation with quiet mode might be that both stdout and stderr are suppressed.

[edorivai]

Could this also be the case for the aws eb CLI? My CI build is passing while running aws elasticbeanstalk create-application-version, even though the CLI outputs

A client error (InvalidParameterValue) occurred when calling the CreateApplicationVersion operation: Application Version 1a0a45f1496e5f5fe2fffa6450138c078571e78e already exists.

as I would expect. The fact that my CI build passes leads me to believe that the message is printed to stdout instead of stderr.