start survey edit iunput validation

When add multiple empty question and submit, warning is generated, but empty questions are merged.
This is not a problem, but you can avoid changing the whole indentation of the else branch by 
```javascript
if (err) {
 return res.render(...); 
}
//async stuff
```
The point of this is that, once you changed the indentation, you touched so many lines, and they will all "blame" to you(when you run git blame <filename>, you will see that you made the changes). Another thing is indentation change is not easy to review, especially in Github, all I can see is you removed hundreds of lines and add them back, I can hardly see the difference. I'm not telling you that you can't change indentation any more, do it when necessary. The commit is not about adding as more lines as possible, I believe is adding as less as possible