Fix null pointer deref.

src/core/core.cpp

@@ -240,7 +240,8 @@ struct System::Impl {
     }
 
     void Shutdown() {
-        // Log last frame performance stats
+        // Log last frame performance stats if game was loded
+        if (perf_stats) {
            const auto perf_results = GetAndResetPerfStats();
            telemetry_session->AddField(Telemetry::FieldType::Performance, "Shutdown_EmulationSpeed",
                                        perf_results.emulation_speed * 100.0);
@@ -250,6 +251,7 @@ struct System::Impl {
                                        perf_results.frametime * 1000.0);
            telemetry_session->AddField(Telemetry::FieldType::Performance, "Mean_Frametime_MS",
                                        perf_stats->GetMeanFrametime());
+        }
 
         lm_manager.Flush();