SERVER-50549 proposes new error codes for proxied commands to be returned in place of connection-relevant error codes in the proxy-forwarded command.

Certainly a client-driver needs to know that the connection experiencing an error is not the client-proxy connection. But it would be obviously nice to know which connection DID have the problem. So this ticket proposes an attachment of diagnostic metadata to the proxied connection error wrapper code (or codes), probably through ErrorExtraInfo mechanism. This metadata is not intended to be acted upon by client drivers.