Fix fatal errors on PHP 7.4

[dkotter]

Description of the Change

In #169, return types were added to a few methods to address some deprecation notices showing up if you were using PHP 8.1. We also bumped our minimum PHP version to 7.4 in #170. The problem here is we used the mixed return type in a few places and full support for that wasn't added until PHP 8.

This means anyone running the latest version of this plugin (v4.3.4) and still running PHP 7.4, will end up with fatal errors that cause the plugin to not function.

This PR addresses this by removing the mixed return type and adding the #[\ReturnTypeWillChange] attribute to suppress the deprecation notices for those running PHP 8.1. This should solve both the original issue as well as the newly introduced issue on PHP 7.4.

One thing to note here is once we do bump our minimum PHP version to 8.0, we'll want to remove the use of these attributes.

How to test the Change

In an environment running PHP 7.4, go and configure the plugin. Prior to the changes here, you'll end up with a fatal error when the container settings are rendered. After this change, things should load as expected.

In an environment running PHP 8.0+, go and configure the plugin. Everything should work as expected and no deprecation warnings should be logged.

Changelog Entry

Fixed - Ensure things work on PHP 7.4

Credits

Props @dkotter

Checklist:

• I agree to follow this project's Code of Conduct.
• I have updated the documentation accordingly.
• I have added tests to cover my change.
• All new and existing tests pass.

[dkotter]

Note that #178 is an alternative to this PR. We don't want to merge both of those in, we just need to decide which of these two is the right path forward.

[Sidsector9]

LGTM 👍

@dkotter IMO we can go ahead with this instead of PR #178 as WordPress itself supports PHP min 7.4.

[mrmt]

Hi,
We were quite distressed by this problem, and this PR solved the issue.
I hope you will release this fix for other people suffering from the same problem. Thanks!!