title: Closing mongoDB connection
body: <p>Server did not close the connection, and I can't find the error.</p>
  <p>When I first access the server (localhost), it returns proper result.</p>
  <p>But next time, it sends warnings like</p>
  <blockquote>
  <p>[MONGODB DRIVER] Warning: the options [caseTranslate] is not supported</p>
  </blockquote>
  <p>and some more.
  Then it returns &quot;Error&quot;</p>
  <pre><code>async function report(prodNum) {
      try{
          await client.connect();
          let res = await findOneByprodNum(client, prodNum);
          return res;
      } catch (e){
          return &quot;Error&quot;;
      } finally {
          client.close();
      }
  }
  
  async function findOneByprodNum(client, prodOfListing) {
      const result = await client.db(&quot;mobileContents&quot;).collection(&quot;food&quot;).findOne({
          prodNum: prodOfListing
      });
      if (result) {
          console.log(`Found Name, in: ${prodOfListing}`);
          console.log(result);
          return result;
      } else {
          console.log(`No listings found, in: ${prodOfListing}`);
          return null;
      }
  }
  </code></pre>
  <p>Client =</p>
  <pre><code>const client = new MongoClient(uri, {
      useUnifiedTopology: true,
      useNewUrlParser: true,
      connectTimeoutMS: 30000
  });
  </code></pre>