How to fix Undefined index: ActiveForm error in compiled Smarty template in Yii2?

Question

Yii

The Smarty template renders a form:

{use class='yii\widgets\ActiveForm' type='block'}
{ActiveForm assign='form' id='login-form' action='/form-handler' options=['class' => 'form-horizontal']}
    {$form->field($model, 'firstName')}
    <div class="form-group">
        <div class="col-lg-offset-1 col-lg-11">
            <input type="submit" value="Login" class="btn btn-primary" />
        </div>
    </div>
{/ActiveForm}

The Smarty template file is saved. This page of the site in the browser is updated - everything is fine. But when the page is refreshed again, an error occurs: Undefined index: ActiveForm. That is, when you re-access this page, the code is taken from the compiled template file, in which the following code:

<?php
        $_smarty_tpl->getGlobal('_viewRenderer')->widgets['blocks']['ActiveForm'] = 'yii\widgets\ActiveForm';
        try {
          $_smarty_tpl->registerPlugin('block', 'ActiveForm', [$_smarty_tpl->getGlobal('_viewRenderer'), '_widget_block__ActiveForm']);
        } catch (SmartyException $e) {
          /* Ignore already registered exception during first execution after compilation */
        }
        ?>   
        <?php $_smarty_tpl->smarty->_tag_stack[] = array('ActiveForm', array('assign' => 'form', 'id' => 'login-form', 'action' => '/backend/login/', 'options' => array('class' => 'uk-panel uk-panel-box uk-form')));
        $_block_repeat = true;
        echo $_smarty_tpl->smarty->registered_plugins['block']['ActiveForm'][0][0]->_widget_block__ActiveForm(array('assign' => 'form', 'id' => 'login-form', 'action' => '/backend/login/2', 'options' => array('class' => 'uk-panel uk-panel-box uk-form')), null, $_smarty_tpl, $_block_repeat);
        while ($_block_repeat) {
          ob_start(); ?>

      <?php echo $_smarty_tpl->tpl_vars['form']->value->field($_smarty_tpl->tpl_vars['model']->value, 'username')->textInput(array('placeholder' => $_smarty_tpl->tpl_vars['model']->value->getAttributeLabel('username'), 'class' => 'form-group5'))->label(false); ?>

      <?php echo $_smarty_tpl->tpl_vars['form']->value->field($_smarty_tpl->tpl_vars['model']->value, 'password')->passwordInput(array('placeholder' => $_smarty_tpl->tpl_vars['model']->value->getAttributeLabel('password')))->label(false); ?>

Answer 1

off-topic.
what a quiet horror. why do you complicate your life with third-party template engines? php is great as a template engine. in conjunction with yii even more so. if you have already learned the smart workbench, then it is even easier for him to learn php