aws-vault: Error on no credentials in kwallet is confusing

When trying to use kwallet without first adding the credentials, the error is:

aws-vault: error: Failed to get credentials for default: unexpected end of JSON input

Only the debug output provides proper answer:

2019/03/30 19:49:06 [keyring] Considering backends: [kwallet]
2019/03/30 19:49:06 Loading config file /home/viraptor/.aws/config
2019/03/30 19:49:06 Parsing config file /home/viraptor/.aws/config
2019/03/30 19:49:06 Skipping session token and using master credentials directly
2019/03/30 19:49:06 Looking up keyring for default
2019/03/30 19:49:06 Error from keyring unexpected end of JSON input
2019/03/30 19:49:06 Failed to find credentials for profile "default" in keyring

aws-vault should interpret / report the missing credentials properly in this case rather than a JSON parsing failure.

Running aws-vault from master with kwallet 5.54.0