fix panic on json.RawMessage parse

[GoWebProd]

If we use this struct

type Thread struct {
	ID                     string          `db:"id" json:"id"`
	Corresponds   json.RawMessage `db:"correspondents" json:"correspondents"`
}

Insert panics because json.RawMessage is alias for []byte but interface can't be casted to it

[xiam]

Thanks! good finding