fix(api): ensure getRecentGifs doesn't error when response is empty

Because the BLOB retrieved from the database can be empty, umarshalling
the data into JSON causes an error.

The API should simply return an empty list of there are no recent gifs.

services/gif/gif.go

@@ -131,12 +131,15 @@ func (api *API) GetRecentGifs() (recentGifs []Gif, err error) {
 	if err != nil {
 		return nil, err
 	}
+	recentGifs = make([]Gif, 0)
 	savedRecentGifs := []Gif{}
+	if len(gifs) > 0 {
 		err = json.Unmarshal(gifs, &savedRecentGifs)
 		if err != nil {
 			return nil, err
 		}
 		recentGifs = savedRecentGifs
+	}
 	return recentGifs, nil
 }