Codechange: Check command callbacks registration even in single player

src/command_func.h

@@ -39,6 +39,7 @@ namespace citymania {
 static const CommandCost CMD_ERROR = CommandCost(INVALID_STRING_ID);
 
 void NetworkSendCommand(Commands cmd, StringID err_message, CommandCallback *callback, CompanyID company, const CommandDataBuffer &cmd_data);
+bool IsNetworkRegisteredCallback(CommandCallback *callback);
 
 bool IsValidCommand(Commands cmd);
 CommandFlags GetCommandFlags(Commands cmd);
@@ -208,6 +209,7 @@ public:
 	template <typename Tcallback>
 	static bool Post(StringID err_message, Tcallback *callback, Targs... args)
 	{
+		assert(::IsNetworkRegisteredCallback(reinterpret_cast<CommandCallback *>(reinterpret_cast<void(*)()>(callback))));
 		return InternalPost(err_message, callback, true, false, std::forward_as_tuple(args...));
 	}
 

src/network/network_command.cpp

@@ -113,6 +113,16 @@ inline auto MakeCallbackTable(std::index_sequence<i...>) noexcept
 /** Type-erased table of callbacks. */
 static const auto _callback_table = MakeCallbackTable(std::make_index_sequence<_callback_tuple_size>{});
 
+/**
+ * Helper function to ensure that callbacks used when Posting commands are actually registered for the network calls.
+ * @param callback The callback to check.
+ * @return \c true when the callback is in the callback table, otherwise \c false.
+ */
+bool IsNetworkRegisteredCallback(CommandCallback *callback)
+{
+	return std::ranges::find(_callback_table, callback) != _callback_table.end();
+}
+
 template <typename T> struct CallbackArgsHelper;
 template <typename... Targs>
 struct CallbackArgsHelper<void(*const)(Commands, const CommandCost &, Targs...)> {