livejson pretty error

error.py

import livejson
import datetime
def save_new_count2(username, count):
    date = datetime.datetime.now().strftime("%Y-%m-%d %H:%M:%S")
    with livejson.File("../db2.json", pretty=True) as db:
        try:
            db[username][date] = count
        except:
            db[username] = {}
            db[username][date] = count


if __name__ == "__main__":

    import time
    save_new_count2('lukaskollmer', 5)
    save_new_count2('luketaylor', 5)
    time.sleep(2)
    save_new_count2('lukaskollmer', 10)
    save_new_count2('luketaylor', 10)
    time.sleep(2)
    save_new_count2('lukaskollmer', 15)
    save_new_count2('luketaylor', 15)