PHP 8 - Warning: Trying to access array offset on value of type bool

[michaelbeil]

Describe the bug As reported in ticket 414077 (moderators only), there is an error shown on /wp-admin/admin.php?page=pmpro-limitpostviews with PHP 8.

To Reproduce Steps to reproduce the behavior:

1. Upgrade to PHP 8
2. Go to /wp-admin/admin.php?page=pmpro-limitpostviews
3. Scroll down see error: Warning: Trying to access array offset on value of type bool in /Users/michaelbeil/Local Sites/test/app/public/wp-content/plugins/pmpro-limit-post-views/adminpages/limitpostviews.php on line 36

Screenshot

Expected behavior There should not be an error shown.

Isolating the problem:

• [x] I have deactivated other plugins and confirmed this bug occurs when only Paid Memberships Pro and is active.
• [x] This bug happens with a default WordPress theme active, or Memberlite.
• [x] I can reproduce this bug consistently using the steps above.

WordPress Environment

``` Paid Memberships Pro 2.7.5, Limit Post Views Add On .6, Twenty Twenty-One 1.4, WordPress 5.9.2, and PHP 7.4.1. ```

[michaelbeil]

Reported in ticket 420731 (moderators only) with PHP 7.4.28.