Cakephp3 pass (custom) validation to flash message

It is simple to pass a message to flash via:

$this->Flash->error(__('The user could not be saved. Please, try again.'));

But when there are more errors from:

$package->errors();

I use just a simple foreach loop:

foreach ($package->errors() as $error=>$value)
{
    foreach ($value as $single_error)
    {
        $error_array[] = ($single_error);
    }
}

Then I pass it to a flash element:

$this->Flash->custom($error_array, [
                 'key' => 'custom']);

And in the flash message:

if ($message > 0) {
    foreach ($message as $m) {
        echo h($m).'<br />';
    }
} else {
    echo h($message);
}

I wonder it here is a better way of handling an array of validation errors.

I am using the following method if there are errors:

Controller:

$errors = $action->errors();
$errorMessages = [];

array_walk_recursive($errors, function($a) use (&$errorMessages) { $errorMessages[] = $a; });

$this->Flash->error(__('Your action cannot be saved!'), ['params' => ['errors' => $errorMessages]]);

Template/Element/Flash/error.tcp:

<?php if (isset($params) AND isset($params['errors'])) : ?>
        <ul class="collection with-header">
            <li class="collection-header"><h5><?= __('The following errors occurred:') ?></h5></li>
    <?php foreach ($params['errors'] as $error) : ?>
            <li class="collection-item"><i class="material-icons">error</i><?= h($error) ?></li>
    <?php endforeach; ?>
        </ul>
<?php endif; ?>

Result:

Just for anyone interested, I am using MaterializeCSS.