Recovery Mode email being sent on non-protected endpoints

[TimothyBlynJacobs]

At some point during the shuffle, usage of the is_protected_endpoint function was dropped. We should decide whether this should be reintroduced or the function removed.

At one point we discussed only sending the Recovery Mode email if the error occurs in a protected endpoint. Then, once the user is in recovery mode, any fatal errors ( even if they aren't in a protected endpoint ) are handled and the plugin will be paused. The idea being to reduce the potential email noise to places where the fatal error could be interfering with the login and WP-Admin experience.

[TimothyBlynJacobs]

I've added a patch which implements only sending the email if the error occurs on a protected endpoint.

Related slack meeting: ​https://wordpress.slack.com/archives/C60K3MP2Q/p1551110798043600

[TimothyBlynJacobs]

This was unintentionally dropped in this commit to the original PR, ​https://github.com/wp-core-php/wordpress-develop/pull/6/commits/917226bcd9d5a73e470f08d4ab7ab8efb0e7c4c4, when we reorganized.

[TimothyBlynJacobs]

This was discussed in #core-php, ​https://wordpress.slack.com/archives/C60K3MP2Q/p1555512749148500, and it looks like the path forward is to add the check to not send the email on protected endpoints.

In addition, the error template would be modified so that when on a protected endpoint to indicate to the user that they can check the admin email address for further instructions. The exact language to use is being worked on.

ie going from The site is experiencing technical difficulties. to something like The site is experiencing technical difficulties. Please check your site admin email inbox for instructions.

Importantly, this screen can be shown to any user, not necessarily the site admin themselves.

[SergeyBiryukov]

In 45238:

Bootstrap/Load: Only send the recovery mode email if the error occurs on a protected endpoint.

This reduces the potential email noise to places where the fatal error could be interfering with the login and admin experience.

Once the user is in recovery mode, any fatal errors (even if they aren't in a protected endpoint) are handled and the plugin or theme will be paused.

Props TimothyBlynJacobs.
See #46950.

[spacedmonkey]

In 46950.2.diff includes text changes agreed in #core-php chat. See comment #8.

These need to committed asap because of the string freeze.

[SergeyBiryukov]

In 45263:

Bootstrap/Load: Modify the fatal error template to indicate to the user that they can check the admin email address for further instructions.

Props spacedmonkey, TimothyBlynJacobs.
Fixes #46950.