mark article as to be deleted (since we have only ad-hoc articles)

src/core/sale.cpp

@@ -24,6 +24,8 @@ void Sale::removeArticle(const Article* articlePtr)
                            [&articlePtr](auto art) { return art.get() == articlePtr; });
     if (it != articles_.end()) {
         (*it)->setSale(nullptr);
+        (*it)->setState(
+            Article::State::DELETE); // since we only have ad-hoc articles, that have all been sold
         articles_.erase(it);
     }
 }