Problem Statement/Rationale

When using mongosh with X.509 credentials, if a user attempts to manually re-authenticate with SCRAM, they get this error:

MongoParseError: [object Object] can only have authSource set to '$external'

This case should error per the auth spec, but the message returned is cryptic, especially due to the "[object Object]" portion.

Steps to Reproduce

Start a mongod server with an X.509 user registered and authentication enabled. After that, these commands should repro the issue:

> mongosh --tlsAllowInvalidHostnames --tls --tlsCAFile <file> --tlsCertificateKeyFile <file>  --authenticationMechanism MONGODB-X509
> use admin
> db.auth("user", "pwd")

Expected Results

An error occurs and the message clearly explains the issue.

Actual Results

An error occurs but the message is a bit cryptic.

Additional Notes

This message is coming from the Node.js driver here, but I'm not sure if the [object Object] display is due to the driver or the shell.

Also, I wanted to file this as an Improvement but didn't see that category, so I filed as bug instead. Feel free to change if there's a better category.