如何解决错误“ OverwriteModelError：编译后无法覆盖Stats模型”？

Question

我被错误OverwriteModelError: Cannot overwrite 'Stats' model once compiled困住了。

首先，我的character.js代码：

const Discord = require('discord.js');
const Stats = require("../models/stats.js");
const Character = require("../models/characters.js");
const mongoose = require('mongoose');
mongoose.connect('mongodb://localhost/AdvendowDatabase', {
  useNewUrlParser: true
});

exports.run = (client, message, args) => {
  if (args[0] === 'help' || args[0] === 'list') {
    let helpEmbed = new Discord.RichEmbed()
      .setAuthor('Character List')
      .setDescription(`All available Characters:\n\nMia - Assassin: 6A, 2D, 100HP\n\nSelect a character with \`<char select charname\``)
      .setFooter(`A = Attack, D = Defence, HP = Health/Hitpoints`);
    message.channel.send(helpEmbed);
  }
  if (args[0] === 'select') {
    let selection = args[1].toLowerCase();
    if (selection) return message.channel.send("Please define a character! <char select >CHARNAME<");
    Stats.findOne({
      userID: message.author.id
    }, (err, charchecker) => {
      if (charchecker) return message.channel.send(`Sorry you already have selected ${charchecker.character}`);
      Character.findOne({
        name: selection
      }, (err, character) => {
        if (!character) return message.channel.send(`There is no character with the name ${selection}! run <char list to see all available characters!`);
        let att = character.attack + 0;
        let def = character.defence + 0;
        let char = character.name;
        let clas = character.class;
        let hp = character.health + 0;
        Stats.findOne({
          userID: message.author.id
        }, (err, stats) => {
          const newChar = new Stats({
            userID: message.author.id,
            character: char,
            class: clas,
            level: 1,
            exp: 0,
            money: 0,
            attack: att,
            defence: def,
            health: hp
          });
          console.log(`[Advendow] ${message.author.username}: registered`);
          newChar.save().catch(err => console.log(err));
          message.channel.send(`[ACCOUNT CREATED]: Your registraiton was succesfull!\nYour Char: ${char} | ${clas}`);
        });
      });
    });
  }
}

exports.help = {
  name: "character",
  name2: "char"
}

Stats.js模型脚本：

const mongoose = require('mongoose');

const statsShema = mongoose.Schema({
  userID: String,
  character: String,
  class: String,
  money: Number,
  level: Number,
  exp: Number,
  attack: Number,
  defence: Number,
  health: Number,

}, {
  collection: 'stats'
});

module.exports = mongoose.model('Stats', statsShema);