Fix for specific/rare issue of {email} variable not saving in "automated mail" settings in some cases in Hustle

hustle-fix-automated-mail-placeholder-not-saving.php

<?php 

/************************************
*
* HUSTLE - fix for {email-1} placeholder not being saved in "automated e-mail" settings
*
* This is a fix for a very specific issue only
*
* author: Prashant Singh/WPMU DEV
*
* Tested with Hustle 7.4.7 only! 
*
* NOTE: EDIT line no. 69 to set your module/popup ID - this is important!
*
**************************************/


add_action('admin_init', 'wpmudev_change_hustle_ajax_method');
function wpmudev_change_hustle_ajax_method(){
	global $wp_filter;
	$tag 			= 'wp_ajax_hustle_save_module';
	$hook_method	= 'save_module';
	$hook_class     = 'Hustle_Modules_Common_Admin_Ajax';

	if ( ! isset( $wp_filter[$tag] ) ) {
		return;
	}

	foreach ( $wp_filter[$tag]->callbacks as $key => $callback_array ) {

		foreach ( $callback_array as $c_key => $callback ) {

			if ( substr_compare( $c_key, $hook_method, strlen( $c_key ) - strlen( $hook_method ), strlen( $hook_method ) ) === 0 ) {
				if ( $callback['function'][0] instanceof $hook_class ){
					unset( $wp_filter[$tag]->callbacks[$key][$c_key] );
				}
			}
		}
	}
	
    add_action( 'wp_ajax_hustle_save_module', 'wpmudev_hustle_save_module' );
}

function wpmudev_hustle_save_module() {

	Opt_In_Utils::validate_ajax_call( 'hustle_save_module_wizard' );

	$module_id = filter_input( INPUT_POST, 'id', FILTER_VALIDATE_INT );
	Opt_In_Utils::is_user_allowed_ajax( 'hustle_edit_module', $module_id );

	$_post = stripslashes_deep( $_POST ); // phpcs:ignore WordPress.Security.NonceVerification.Missing

	$error_array = array();

	try {
		if ( empty( $module_id ) ) {
			throw new Exception();
		}

		$module = Hustle_Module_Collection::instance()->return_model_from_id( $module_id );
		if ( is_wp_error( $module ) ) {
			throw new Exception();
		}

		$_post      = $module->sanitize_module( $_post );
		
		
		// replace the number below - example is 11 - with an ID of your Hustle module/popup		
		if( $module_id == 11 && $_post['emails']['recipient'] == '' ){
		    $_post['emails']['recipient'] = '{email}';
		}
		$validation = $module->validate_module( $_post );
		if ( true !== $validation ) {
			$error_array = array( 'data' => $validation['error'] );
			throw new Exception();
		}

		$updated = $module->update_module( $_post );

		if ( isset( $updated['success'] ) && false === $updated['success'] ) {
			$error_array = array( 'data' => $updated['error'] );
			throw new Exception();
		}

		if ( false === $updated ) {
			$error_array = array( 'data' => $updated );
			throw new Exception();
		}
	} catch ( Exception $e ) {
		wp_send_json_error( $error_array );
	}

	wp_send_json_success();
}