查询mongodb数据时nodejs出现错误？

const MongoClient = require('mongodb').MongoClient;
const url = 'mongodb://localhost:27017/mydb';

MongoClient.connect(url, function(err, db) {
  if (err) throw err;
  console.log('Connected to MongoDB');

  // 在这里执行查询操作
});

const collection = db.collection('mycollection');
collection.find({}).toArray(function(err, result) {
  if (err) throw err;
  console.log(result);
  db.close();
});

collection.find({ name: 'John' }).toArray(function(err, result) {
  if (err) throw err;
  console.log(result);
  db.close();
});

try {
  const result = await collection.find({}).toArray();
  console.log(result);
} catch (err) {
  console.error(err);
} finally {
  db.close();
}