Query validator doens't work
Hello, genius, I found that it seems the query validator doesn't work. Here is my code:
```
const Koa = require('koa')
const app = new Koa()

const router = require('koa-joi-router')
const Joi = router.Joi
const p = router()

p.route({
  path: '/',
  method: 'get',
  validate: {
    query: {
      t: Joi.string().min(3)
    },
    body: {
      email: Joi.string().email()
    },
    type: 'json'
  },
  handler: async ctx => {
    ctx.body = 'hello'
  }

})
p.prefix('/api/v1/public')
app.use(p.middleware())
```
![image](https://user-images.githubusercontent.com/14965190/59023389-4bc77680-8882-11e9-8879-0e2b55ae456e.png)


If the email is missed in the request body, it works very well. However, it doesn't throw any error without a t in the request query even with the email in the body. What's wrong?


![image](https://user-images.githubusercontent.com/14965190/59023346-305c6b80-8882-11e9-9772-0b108b87aaf1.png)
