System: Fix possible race condition in presence update

src/core/system.cpp

@@ -5885,15 +5885,14 @@ void System::UpdateRichPresence(bool update_session_time)
     }
   }
 
+  const auto lock = Achievements::GetLock();
+
   std::string state_string;
   if (Achievements::HasRichPresence())
-  {
-    const auto lock = Achievements::GetLock();
-    state_string = StringUtil::Ellipsise(Achievements::GetRichPresenceString(), 128);
-    rp.state = state_string.c_str();
+    rp.state = (state_string = StringUtil::Ellipsise(Achievements::GetRichPresenceString(), 128)).c_str();
+
   if (const std::string& icon_url = Achievements::GetGameIconURL(); !icon_url.empty())
     rp.largeImageKey = icon_url.c_str();
-  }
 
   dyn_libs::Discord_UpdatePresence(&rp);
 }