title: Error message shown to user when invalid credentials
body: <p>right now I'm trying to make an error message shown to the user if the login credentials are wrong and I just can't get it to work. I use node.js and SQLite for my database. I tried fetching, importing, and exporting but nothing worked. I won't share my front-end code because nothing in there works.</p>
  <p>Here's my whole back-end: <a href="https://pastebin.com/SaQrGq4z" rel="nofollow noreferrer">https://pastebin.com/SaQrGq4z</a>
  And here's the html:</p>
  <p><div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false">
  <div class="snippet-code">
  <pre class="snippet-code-html lang-html prettyprint-override"><code>&lt;!DOCTYPE html&gt;
  &lt;html lang="en"&gt;
  
  &lt;head&gt;
      &lt;link rel="stylesheet" href="main.css"&gt;
      &lt;meta charset="UTF-8"&gt;
      &lt;meta http-equiv="X-UA-Compatible" content="IE=edge"&gt;
      &lt;meta name="viewport" content="width=device-width, initial-scale=1.0"&gt;
      &lt;title&gt;club&lt;/title&gt;
  &lt;/head&gt;
  
  &lt;body&gt;
      &lt;header&gt;
  
      &lt;/header&gt;
      &lt;div id="ClockDisplay" class="clock" onload="showTime()"&gt;&lt;/div&gt;
      &lt;div class="background"&gt;
          &lt;div class="demo"&gt;
              &lt;div class="login"&gt;
                  &lt;div class="login-text"&gt;
                      &lt;span class="glitchanim" data-text=".club"&gt;&lt;/span&gt;
                  &lt;/div&gt;
                  &lt;div class="login-form"&gt;
                      &lt;form action="auth" method="POST" autocomplete="off"&gt;
                          &lt;div class="login-row"&gt;
                              &lt;svg class="login-icon name svg-icon" viewBox="0 0 20 20"&gt;
                                  &lt;path d="M0,20 a10,8 0 0,1 20,0z M10,0 a4,4 0 0,1 0,8 a4,4 0 0,1 0,-8" /&gt;
                              &lt;/svg&gt;
                              &lt;style type="text/css"&gt;
                                  input[name="username"] {
                                      background: transparent;
                                  }
                              &lt;/style&gt;
                              &lt;input type="text" name="username" class="login-input name" id="test"
                                  placeholder="Username" /&gt;
                          &lt;/div&gt;
                          &lt;div class="login-row"&gt;
                              &lt;svg class="login-icon pass svg-icon" viewBox="0 0 20 20"&gt;
                                  &lt;path d="M0,20 20,20 20,8 0,8z M10,13 10,16z M4,8 a6,8 0 0,1 12,0" /&gt;
                              &lt;/svg&gt;
                              &lt;input type="password" name="password" class="login-input pass" placeholder="Password" /&gt;
                          &lt;/div&gt;
                          &lt;p class="login-error"&gt;Username and/or Password do not exist&lt;/p&gt;
                          &lt;input type="submit" value="Sign In"&gt;
                          &lt;p class="login-signup"&gt;Don't have an account? &amp;NonBreakingSpace; &lt;a href="signup.html"&gt;Sign
                                  up&lt;/a&gt;&lt;/p&gt;
                      &lt;/form&gt;
                  &lt;/div&gt;
              &lt;/div&gt;
          &lt;/div&gt;
      &lt;/div&gt;
      &lt;footer&gt;
  
      &lt;/footer&gt;
  
      &lt;script src="main.js"&gt;&lt;/script&gt;
  &lt;/body&gt;
  
  &lt;/html&gt;</code></pre>
  </div>
  </div>
  </p>