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 one of your plugins, enable-media-replace.
Error Details
=============
An error of type E_ERROR was caused in line 128 of the file /home/*******/public_html/wp-content/plugins/enable-media-replace/classes/emr-plugin.php. Error message: Uncaught Error: Class ‘EnableMediaReplace\Notices\NoticeController’ not found in /home/******/public_html/wp-content/plugins/enable-media-replace/classes/emr-plugin.php:128
Stack trace:
#0 /home/********/public_html/wp-includes/class-wp-hook.php(303): EnableMediaReplace\EnableMediaReplacePlugin->init(”)
#1 /home/*******/public_html/wp-includes/class-wp-hook.php(327): WP_Hook->apply_filters(NULL, Array)
#2 /home/*******/public_html/wp-includes/plugin.php(470): WP_Hook->do_action(Array)
#3 /home/********/public_html/wp-admin/admin-ajax.php(45): do_action(‘admin_init’)
#4 {main}
thrown
Enjoy.