fix: debug toolbar logs collector behavior on isEmpty()

[mjomble]

Description
Fixed bug introduced in #9581 and described in this comment

• isEmpty() was checking the opposite
• The checks did not work if $this->data was null

Checklist:

• Securely signed commits
• Component(s) with PHPDoc blocks, only if necessary or adds value (without duplication)
• Unit testing, with >80% coverage
• User guide updated
• Conforms to style guide

[mjomble]

I'll look into adding a unit test for the Logs controller

[mergeable]

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[paulbalandan]

The code change and added test looks good. Thanks for that. However, I'm not sure about adding the default [] to the $data property. Well, theoretically this is a breaking change as the initial state would now be [] instead of null. But, practically speaking, the intent was to treat $data as an array. It's just probably that when this class was created, typed properties were not yet a thing. So, this is a bug fix.

Let's hear from others on their take on this.

[datamweb]

LGTM!

[michalsn]

In this case, I’m fine with treating changes to the $data property as a bug fix, though I hope this doesn't open the door to making similar adjustments too easily in the future.

[michalsn]

@mjomble Please also add a changelog entry, here: https://github.com/codeigniter4/CodeIgniter4/blob/develop/user_guide_src/source/changelogs/v4.6.4.rst#bugs-fixed

PHPStan errors should be gone after merging #9728, so you don't have to worry about it.

Changelog entry is missing

[mjomble]

I've updated the changelog

[paulbalandan]

thank you @mjomble