Improve account validation and feedback

app/Views/auth/login.php

@@ -1,12 +1,45 @@
+<?php
+
+$values = $values ?? ['email' => ''];
+$errors = $errors ?? [];
+?>
+
 <section class="auth-panel">
     <h1>Anmelden</h1>
+    <?php if (!empty($errors['form'])): ?>
+        <p class="field-error" role="alert"><?= e($errors['form']) ?></p>
+    <?php endif; ?>
     <form method="post" action="index.php?route=login" class="form">
         <?= csrf_field() ?>
         <label for="email">E-Mail</label>
-        <input id="email" name="email" type="email" autocomplete="email" required>
+        <input
+            id="email"
+            name="email"
+            type="email"
+            maxlength="190"
+            autocomplete="email"
+            value="<?= e($values['email'] ?? '') ?>"
+            class="<?= !empty($errors['email']) ? 'input-error' : '' ?>"
+            <?= !empty($errors['email']) ? 'aria-invalid="true" aria-describedby="email-error"' : '' ?>
+            required
+        >
+        <?php if (!empty($errors['email'])): ?>
+            <small id="email-error" class="field-error"><?= e($errors['email']) ?></small>
+        <?php endif; ?>
 
         <label for="password">Passwort</label>
-        <input id="password" name="password" type="password" autocomplete="current-password" required>
+        <input
+            id="password"
+            name="password"
+            type="password"
+            autocomplete="current-password"
+            class="<?= !empty($errors['password']) ? 'input-error' : '' ?>"
+            <?= !empty($errors['password']) ? 'aria-invalid="true" aria-describedby="password-error"' : '' ?>
+            required
+        >
+        <?php if (!empty($errors['password'])): ?>
+            <small id="password-error" class="field-error"><?= e($errors['password']) ?></small>
+        <?php endif; ?>
 
         <button type="submit">Einloggen</button>
     </form>