title: ^ TypeError: Invalid schema configuration: `U` is not a valid type at path `0`
body: <pre class="lang-js prettyprint-override"><code>const userSchema = new mongoose.Schema({
      name: {
          type: String,
          required: true,
          unique: true
      },
      password: {
          type: String,
          required: true
      },
      avatar: {
          type: String
      },
  });
      
  module.exports= user = mongoose.Schema('user',userSchema);
  </code></pre>