Assistant: Fix crash when activating empty search result

If there are no search results in the list, we shouldn't do anything
when you try to active the selected result, since there isn't one.

Fix this by using an Optional<size_t> to store the selected index.

1 files changed, 25 insertions, 11 deletions

diff --git a/Userland/Applications/Assistant/main.cpp b/Userland/Applications/Assistant/main.cpp
index 3c4c57b24d..a7cb5ebec0 100644
--- a/Userland/Applications/Assistant/main.cpp
+++ b/Userland/Applications/Assistant/main.cpp
@@ -21,7 +21,7 @@
 namespace Assistant {
 
 struct AppState {
-    size_t selected_index { 0 };
+    Optional<size_t> selected_index;
     Vector<NonnullRefPtr<Result>> results;
     size_t visible_result_count { 0 };
 
@@ -218,23 +218,34 @@ int main(int argc, char** argv)
         db.search(text_box.text());
     };
     text_box.on_return_pressed = [&]() {
-        app_state.results[app_state.selected_index]->activate();
+        if (!app_state.selected_index.has_value())
+            return;
+        app_state.results[app_state.selected_index.value()]->activate();
         exit(0);
     };
     text_box.on_up_pressed = [&]() {
-        if (app_state.selected_index == 0)
-            app_state.selected_index = app_state.visible_result_count - 1;
-        else if (app_state.selected_index > 0)
-            app_state.selected_index -= 1;
+        if (!app_state.visible_result_count)
+            return;
+        auto new_selected_index = app_state.selected_index.value_or(0);
+        if (new_selected_index == 0)
+            new_selected_index = app_state.visible_result_count - 1;
+        else if (new_selected_index > 0)
+            new_selected_index -= 1;
 
+        app_state.selected_index = new_selected_index;
         mark_selected_item();
     };
     text_box.on_down_pressed = [&]() {
-        if ((app_state.visible_result_count - 1) == app_state.selected_index)
-            app_state.selected_index = 0;
-        else if (app_state.visible_result_count > app_state.selected_index)
-            app_state.selected_index += 1;
+        if (!app_state.visible_result_count)
+            return;
+
+        auto new_selected_index = app_state.selected_index.value_or(0);
+        if ((app_state.visible_result_count - 1) == new_selected_index)
+            new_selected_index = 0;
+        else if (app_state.visible_result_count > new_selected_index)
+            new_selected_index += 1;
 
+        app_state.selected_index = new_selected_index;
         mark_selected_item();
     };
     text_box.on_escape_pressed = []() {
@@ -242,7 +253,10 @@ int main(int argc, char** argv)
     };
 
     db.on_new_results = [&](auto results) {
-        app_state.selected_index = 0;
+        if (results.is_empty())
+            app_state.selected_index = {};
+        else
+            app_state.selected_index = 0;
         app_state.results = results;
         app_state.visible_result_count = min(results.size(), MAX_SEARCH_RESULTS);
         results_container.remove_all_children();