fix disconnect when sending mail to offline user

src/ReceiveCommands.cc

@@ -2079,8 +2079,18 @@ static void on_simple_mail(shared_ptr<ServerState> s, shared_ptr<Client> c,
       throw logic_error("invalid game version");
   }
 
-  auto target = s->find_client(nullptr, to_guild_card_number);
+  shared_ptr<Client> target;
+  try {
+    target = s->find_client(nullptr, to_guild_card_number);
+  } catch (const out_of_range&) { }
 
+  if (!target) {
+    // TODO: We should store pending messages for accounts somewhere, and send
+    // them when the player signs on again. We should also persist the player's
+    // autoreply setting when they're offline and use it if appropriate here.
+    send_text_message(c, u"$C6Player is offline");
+
+  } else {
     // If the sender is blocked, don't forward the mail
     for (size_t y = 0; y < 30; y++) {
       if (target->game_data.account()->blocked_senders.data()[y] == c->license->serial_number) {
@@ -2088,7 +2098,8 @@ static void on_simple_mail(shared_ptr<ServerState> s, shared_ptr<Client> c,
       }
     }
 
-  // If the target has auto-reply enabled, send the autoreply
+    // If the target has auto-reply enabled, send the autoreply. Note that we also
+    // forward the message in this case.
     if (!target->game_data.player()->auto_reply.empty()) {
       send_simple_mail(c, target->license->serial_number,
           target->game_data.player()->disp.name,
@@ -2101,6 +2112,7 @@ static void on_simple_mail(shared_ptr<ServerState> s, shared_ptr<Client> c,
         c->license->serial_number,
         c->game_data.player()->disp.name,
         message);
+  }
 }