GETTING ERROR WHILE CLICK ON CUSTOMIZE FROM ADMIN PANEL "CRITICAL ERROR IN SITE"

Hi Team,
we have got a project from our client 2 months back and it’s based on ENFOLD theme and it really going well but a few days back I am getting an error “there is a critical issue in your site”, while click on customize button so we are now stuck in development, also we got an error mail from WordPress so please look into it and help us, we also don’t know about Genuity of the theme because we sign the product in the midway of development, we are also ready to pay for resolution please find out below error and contact if any (Email address hidden if logged out) , +917008035073

Error Mail:
Howdy!

Since WordPress 5.2 there is a built-in feature that detects when a plugin or theme causes a fatal error on your site and notifies you with this automated email.

In this case, WordPress caught an error with your theme, Enfold.

First, visit your website (https://www.happymovermsct.com/) and check for any visible issues. Next, visit the page where the error was caught (https://www.happymovermsct.com/wp-admin/customize.php?url=https%3A%2F%2Fwww.happymovermsct.com%2F) and check for any visible issues.

Please contact your host for assistance with investigating this issue further.(already contacted to host partner and they said theme issue )

If your site appears broken and you can’t access your dashboard normally, WordPress now has a special “recovery mode”. This lets you safely log in to your dashboard and investigate further.

https://www.happymovermsct.com/wp-login.php?action=enter_recovery_mode&rm_token=2j5RKG2vmwacHi5LZ2EoPE&rm_key=CR4tVkl970GMnMDNA8sjNg

To keep your site safe, this link will expire in 1 day. Don’t worry about that, though: a new link will be emailed to you if the error occurs again after it expires.

When seeking help with this issue, you may be asked for some of the following information:
WordPress version 5.8
Current theme: Enfold (version 4.6.3.1)
Current plugin: (version )
PHP version 7.4.22

Error Details
=============
An error of type E_ERROR was caused in line 619 of the file /home/webclexc/happymovermsct.com/wp-content/themes/enfold/config-gutenberg/class-avia-gutenberg.php. Error message: Uncaught TypeError: Argument 2 passed to Avia_Gutenberg::handler_display_post_states() must be an instance of WP_Post, null given, called in /home/webclexc/happymovermsct.com/wp-includes/class-wp-hook.php on line 303 and defined in /home/webclexc/happymovermsct.com/wp-content/themes/enfold/config-gutenberg/class-avia-gutenberg.php:619
Stack trace:
#0 /home/webclexc/happymovermsct.com/wp-includes/class-wp-hook.php(303): Avia_Gutenberg->handler_display_post_states(Array, NULL)
#1 /home/webclexc/happymovermsct.com/wp-includes/plugin.php(189): WP_Hook->apply_filters(Array, Array)
#2 /home/webclexc/happymovermsct.com/wp-admin/includes/template.php(2239): apply_filters(‘display_post_st…’, Array, NULL)
#3 /home/webclexc/happymovermsct.com/wp-includes/nav-menu.php(831): get_post_states(NULL)
#4 [internal function]: wp_setup_nav_menu_item(Object(WP_Post))
#5 /home/webclexc/happymovermsct.com/wp-includes/nav-menu.php(755): array_map(‘wp_setup_nav_me…’, Array)
#6 /home/webclexc/happymovermsct.com/wp-content/plugins/