多进程启动报错

egg多进程启动时报错

```shell
SyntaxError: Unexpected end of JSON input
    at JSON.parse (<anonymous>)
    at IncomingMessage.<anonymous> (/yhsd-api/lib/Request.js:107:23)
    at IncomingMessage.emit (events.js:194:15)
    at endReadableNT (_stream_readable.js:1103:12)
    at process._tickCallback (internal/process/next_tick.js:63:19)
```