Improve logs when connection fails

[Mereck13579]

Works normally with password but on private key the connection drops without connecting properly.
On the other end the auth logs (some data are obfuscated for privacy):
Oct 26 12:46:09 fubuki sshd[109840]: Connection reset by authenticating user XXX 91.XXX.XXX.254 port 19177 [preauth]

I also couldn't find any log, and the lack of documentation on what keys are accepted doesn't really help me see if I did something wrong here or not (tried with both an older SHA1 RSA key and an ed25519 key)

[ggrandes]

I have tried using an RSA key and it works correctly, if I use another RSA key that is not authorized on the remote server, the error I see on the remote is similar to yours.

Connection reset by invalid user test 83.xxx.xxx.xxx port 20264 [preauth]

This does not seem like a bug, but it is necessary to see how to improve the logs.