Issue #3521265 :Fix search term missing error.

Closes #3521265

modules/fontawesome_iconpicker_widget/src/IconManagerService.php

@@ -196,8 +196,12 @@ class IconManagerService implements IconManagerServiceInterface {
     $terms_list = [];
     foreach ($icons as $properties) {
       foreach ($properties['classes'] as $item) {
-        array_push($properties['search_terms'], $properties['name']);
-        $terms_list[] = $properties['search_terms'];
+        $search_terms = $properties['search_terms'] ?? [];
+        if (!is_array($search_terms)) {
+          $search_terms = [];
+        }
+        $search_terms[] = $properties['name'];
+        $terms_list[] = $search_terms;
       }
     }
     return $terms_list;