android: SettingsFragmentPresenter: Fix a nullptr exception with loadSettingsList.

src/android/app/src/main/java/org/citra/citra_emu/features/settings/ui/SettingsFragmentPresenter.java

@@ -99,6 +99,10 @@ public final class SettingsFragmentPresenter {
         }
         ArrayList<SettingsItem> sl = new ArrayList<>();
 
+        if (mMenuTag == null) {
+            return;
+        }
+
         switch (mMenuTag) {
             case SettingsFile.FILE_NAME_CONFIG:
                 addConfigSettings(sl);