gosh...

        try {
            val user = authService.register(registrationRequest.email, registrationRequest.password)

            return user
        } catch (exception: Exception) {
            // log exception
            throw exception
        }

no, no, no!

the whole point of the exceptions (and moreso of the unchecked ones) is to be transparent!

if you don't know what to do with an exception do NOT try to handle it

that snippet should just be

    return authService.register(registrationRequest.email, registrationRequest.password)