Chess: Make the resign button have no effect after the game ends

Author: https://github.com/tcl3
Commit: b7f4363791
Pull-request: https://github.com/SerenityOS/serenity/pull/18945
Reviewed-by: https://github.com/gmta ✅

Userland/Games/Chess/ChessWidget.cpp

@@ -680,6 +680,10 @@ void ChessWidget::flip_board()
 
 int ChessWidget::resign()
 {
+    // FIXME: Disable the resign checkbox if the game is finished
+    if (board().game_finished())
+        return -1;
+
     if (want_engine_move()) {
         GUI::MessageBox::show(window(), "You can only resign on your turn."sv, "Resign"sv, GUI::MessageBox::Type::Information);
         return -1;