Replace strlen with custom callback that accepts null

[delawski]

Fixes #1349
Supersedes #1466

This fixes a deprecation notice in PHP 8:

PHP Deprecated: strlen(): Passing null to parameter #1 ($string) of type string is deprecated in classes/class-log.php on line 217

It addressed the review feedback left on #1466 which pointed out that null values should be filtered out from the array.

In the end, keeping or removing null values in this particular scenario does not seem to matter. The $exclude_rules array is only passed to the record_matches_rules() method which ignores null values anyway:

stream/classes/class-log.php

Line 235 in d6d707e

if ( ! isset( $record[ $exclude_key ] ) || is_null( $exclude_value ) ) {

However, for the sake of keeping the business logic the same, I've opted for this approach instead of the one in #1466.

Checklist

• Project documentation has been updated to reflect the changes in this pull request, if applicable.
• I have tested the changes in the local development environment (see contributing.md).
• I have added phpunit tests.

[tharsheblows]

I'm approving but not merging -- mainly because I want to make sure I understand what's going on in the bit above it. Once you've had a look, you can merge!

[tharsheblows]

@delawski I am approving this but I think all we need is a check on is_null()? I'm kind of asking because I want to make sure I understand the bit above it 😊

[delawski]

I absolutely love your reviews, @tharsheblows! You're totally right about the second check (removed in 9d47e25) - in this scenario it's redundant since we are explicitly setting every empty property to null above.

One of the solutions I was considering and trying out involved setting the properties above to empty strings instead of null so that the original strlen-based solution would still work. I guess I got lost somewhere in between 😅