Add a message to explain why connection are closed in case of invalid player names

rust/sea_battle_backend/src/human_player_ws.rs

@@ -152,6 +152,7 @@ impl Actor for HumanPlayerWS {
     fn started(&mut self, ctx: &mut Self::Context) {
         // Check player name length
         if self.name.len() < MIN_PLAYER_NAME_LENGTH || self.name.len() > MAX_PLAYER_NAME_LENGTH {
+            log::error!("Close connection due to invalid user name!");
             ctx.stop();
             return;
         }