Current version:
In the current version, if we generate a schema from JSON with null data will cause an error
Example:

json = {
  "data": null
}

What I proposed is:
Checking the value is type of nil, something like this:

func getType(item interface{}) string {
	switch item.(type) {
	case string:
		return "string"
	...
	case nil:
		return "nil"
	default:
		var r = reflect.TypeOf(item)
		return fmt.Sprintf("%s", r.String())
	}
}

This feature will make sure no error happened when getting null value from response body.

For example:

{
 "data":[
     [1,2,4], 
     [27,23,62]
   ]
}