feat(login.html): display error if provided

judas_server/web/templates/login.html

@@ -11,12 +11,20 @@
         <header>
             <h1><a href="{{ url_for('index') }}">judas</a></h1>
         </header>
-        <main class="center">
-            <form method="post">
+        <main>
+            <h1>Login</h1>
+            <form method="post" class="center">
                 <label for="password">Password:</label>
                 <input type="password" id="password" name="password" required>
-                <br><br>
+                <br>
+                <br>
                 <input type="submit" value="Login" class="button">
+                {% if error %}
+                <div class="error-container">
+                    <h1>Login failure</h1>
+                    <p>{{ error }}</p>
+                </div>
+                {% endif %}
             </form>
         </main>
     </div>