Fatal error in a mu-plugin causes WSoD protection handler to trigger a warning

[johnbillion]

Given a mu-plugin that triggers a fatal error immediately upon execution, the WSoD protection handler additionally triggers a warning of its own:

Warning: Invalid argument supplied for foreach() in wp-includes/error-protection.php on line 71

The $wp_theme_directories has not been populated at this early point, and therefore triggers this error.

[flixos90]

In 44706:

Bootstrap/Load: Fix notice when theme directories are not populated yet.

When a fatal error occurs outside of a regular plugin in a stage where theme directories are not set up yet (for example in a MU plugin), this would previously trigger a notice.

Props johnbillion.
Fixes #46068. See #44458.

[flixos90]

In 44717:

Bootstrap/Load: Revert fatal error recovery mechanism from 5.1 to polish for 5.2.

Due to the high number of follow-up tickets and associated security concerns, it was decided to reschedule the fatal error recovery feature for WordPress 5.2, in order to address these issues properly. The feature will continue to be developed, with iterations being merged into trunk early in the 5.2 release cycle.

Fixes #46141. See #44458, #45932, #45940, #46038, #46047, #46068.

[flixos90]

This ticket is based on the old fatal error recovery mode implementation and will be covered as part of #46130.