fix: early return when hotkey not found in map

Avoid sending events for unregistered hotkeys and passing invalid
values to keybinder_unbind by returning early when lookup fails.

Author: dongfengweixiao

packages/hotkey_manager_linux/linux/hotkey_manager_linux_plugin.cc

@@ -32,14 +32,14 @@ G_DEFINE_TYPE(HotkeyManagerLinuxPlugin,
               g_object_get_type())
 
 void handle_key_down(const char* keystring, void* user_data) {
-  const char* identifier;
-
   std::string val = keystring;
   auto result = std::find_if(hotkey_id_map.begin(), hotkey_id_map.end(),
                              [val](const auto& e) { return e.second == val; });
 
-  if (result != hotkey_id_map.end())
-    identifier = result->first.c_str();
+  if (result == hotkey_id_map.end())
+    return;
+
+  const char* identifier = result->first.c_str();
 
   g_autoptr(FlValue) event_data = fl_value_new_map();
   fl_value_set_string_take(event_data, "identifier",
@@ -103,14 +103,16 @@ static FlMethodResponse* hkm_unregister(_HotkeyManagerLinuxPlugin* self,
                                         FlValue* args) {
   const char* identifier =
       fl_value_get_string(fl_value_lookup_string(args, "identifier"));
-  const char* keystring;
 
   std::string val = identifier;
   auto result = std::find_if(hotkey_id_map.begin(), hotkey_id_map.end(),
                              [val](const auto& e) { return e.first == val; });
 
-  if (result != hotkey_id_map.end())
-    keystring = result->second.c_str();
+  if (result == hotkey_id_map.end())
+    return FL_METHOD_RESPONSE(
+        fl_method_success_response_new(fl_value_new_bool(false)));
+
+  const char* keystring = result->second.c_str();
 
   keybinder_unbind(keystring, handle_key_down);
   hotkey_id_map.erase(identifier);