If a user try to register with an already used email the error is misleading

[RoyBellingan]

Returned

There was an unexpected error. Please try again later.

Should be

Email already in use

[RoyBellingan]

I think the error arise from a difference between mysql and mariadb (I am running mariadb 11.0.2)

The error returned by mariadb is Duplicate entry 'spam@seisho.us' for key 'email'

The expected one would have been

The error returned by mariadb is Duplicate entry 'spam@seisho.us' for key 'users.email'

The fix is just to replace the string check there
https://github.com/anarthal/servertech-chat/blob/master/server/src/services/mysql_client.cpp#L262
https://github.com/anarthal/servertech-chat/blob/master/server/src/services/mysql_client.cpp#L265

I will not open a pull request as it will take more time than editing on the fly those 2 lines.

[anarthal]

Thanks for the catch. That's a non-potability between MySQL and MariaDB, which is indicating this is not the right way to handle it. We probably want to inspect the exiting user on failure to determine what happened, or an equivalent strategy. What you propose is an acceptable workaround as long as you're running MariaDB.

[RoyBellingan]

The workaround above also work for mysql btw.
I checked and looks like is not possible to have a deterministic way to see which column went in collision -.-

In theory, but not for now, is possible to read on connection what DB is beeing used, and have a dedicated list to intercept those kind of error... ?