Symfony \ Component \ Debug \ Exception \ FatalThrowableError: не удалось преобразовать объект класса WP_Error

Question

Я работаю над сайтом, мы столкнулись с этой проблемой после обновления до php 7.4.

2020/01/08 14:16:53 [error] 119756#119756: *2141466 FastCGI sent in stderr: "PHP message: PHP Fatal error: Uncaught Symfony\Component\Debug\Exception\FatalThrowableError: Object of class WP_Error could not be converted to string in .../app/controllers/app.php:655
Stack trace:
    #0 .../uploads/cache/63d45ed2d399b6699282702966fd54defe5b7ea3.php(2): App\App::caseyCategoryChooser()
    #1 .../casey-pro/vendor/illuminate/view/Engines/PhpEngine.php(43): include('/www/casey_176/...')
    #2 .../casey-pro/vendor/illuminate/view/Engines/CompilerEngine.php(59): Illuminate\View\Engines\PhpEngine->evaluatePath('/www/casey_176/...', Array)
    #3 .../casey-pro/vendor/illuminate/view/View.php(142): Illuminate\View\Engines\CompilerEngine->get('/www/casey_176/...', Array)
    #4 .../casey-pro/vendor/illuminate/view/View.php(125): Illuminate\View\View->getContents()
    #5 .../public/" while reading response header from upstream, client: 54.36.150.61, server: casey.hu, request: "GET /termekek/tokok/szuro/mobil/

<div class="item-wrap level1" <?php if(wp_is_mobile() && $cat ==$main_category->slug && $subcategory !=false){echo "style='display:block'" ;}elseif (wp_is_mobile()) {
    echo "style='display:none'";
}  ?>
>
    <a href=<?= $main_category_url ?> class="item type-icon-text">  //this lis line 656
        <i class="<?= $main_category_icon ?>"></i>
        <h2 class="text"><?= $main_category->name?></h2>
    </a>
</div>

<?php
//<!-- KIJELÖLT ALKATEGÓRIA HA NINCS AKTÍV FILTER (MINDEN, KIVÉVE TOK & FÓLIA) -->
if($subcategory && !$attributes):
    $subcategory_url = get_term_link($subcategory->term_id, 'product_cat');
    $class_text = get_field('category_icon', 'product_cat_'.$subcategory->term_id);
    $subcategory_icon = "casey-" . $class_text;
    $children_subcategory= get_terms($subcategory->taxonomy, array(
    'parent'    => $subcategory->term_id
    ) );
    $resp_name = $subcategory->name;
    ?>
    <div class="item-wrap level2" <?php if(wp_is_mobile() && $cat ==$subcategory->slug){
        echo "style='display:none'" ;
        $display_cat=1;
    }elseif (wp_is_mobile()) {
    echo "style='display:none'";
}  ?>>

Это строка 656: class = "item type-icon-text" >

Кэшированная трассировка файла, строка 2:

?php $__env->startSection('content'); ?>

  <div id="back_to_top">
    <img src="<?= App\asset_path('images/back_to_top.svg'); ?>" alt="">
    <div id="back_to_top_sign">oldal tetejére</div>
  </div>