Presence of empty AWS_DEFAULT_PROFILE env var breaks the CLI

[diversario]

If AWS_DEFAULT_PROFILE exists in the environment and is empty:

❯ AWS_DEFAULT_PROFILE= AWS_PROFILE=not-default-one mssh ubuntu@i-aaaaaaaaaaaaa
The config profile () could not be found

Additionally, if AWS_DEFAULT_PROFILE is set to anything, the tool ignores any other profile indication and always uses the default profile.