Warning: Illegal string offset 'view_subs' in /wp-content/plugins/ninja-forms/includes/register.php on line 145

Fatal error: Uncaught Error: Cannot use string offset as an array in /wp-content/plugins/ninja-forms/includes/register.php:145 Stack trace: #0 /wp-content/plugins/ninja-forms/includes/admin/pages/ninja-forms-subs/tabs/view-subs/sidebars/select-subs.php(105): ninja_forms_register_sidebar_option('view_subs', Array) #1 /wp-includes/plugin.php(525): ninja_forms_register_select_sub_submit('') #2 /wp-settings.php(393): do_action('init') #3 /wp-config.php(91): require_once('/wp-settings.ph...') #4 /wp-load.php(37): require_once('/wp-config.php') #5 /wp-blog-header.php(13): require_once('/wp-load.php') #6 /index.php(17): require('/wp-blog-header...') #7 {main} thrown in /wp-content/plugins/ninja-forms/includes/register.php on line 145