yern electron:serve時にワーニングが大量に出る

このようなログが大量に出る．

```
2020-10-03 21:23:18.847 Electron Helper (Renderer)[44653:6413184] CoreText note: Client requested name ".AppleJapaneseFont-Regular", it will get Times-Roman rather than the intended font. All system UI font access should be through proper APIs such as CTFontCreateUIFontForLanguage() or +[NSFont systemFontOfSize:].
```
