Unable to mock function to return an empty array.

[peterwilsoncc]

Describe the bug
In Distributor, I am attempting to mock a function to return an empty array:

https://github.com/10up/distributor/blob/74ba9c5110de1dfa3415e76eab7d7ffc87b19e49/tests/php/SubscriptionsTest.php#L321-L325

However, the return value is coming back as NULL.

As an alternative approach, I've tried setting the return attribute as a callable function(){ return []; } but the same issue occurs.

To Reproduce

1. As a reduced test case, create the test:

    public function test_return_empty_array() {
    	$post_id = 1;
    	\WP_Mock::userFunction(
    		'\Distributor\Utils\peters_test_function', [
    			'return' => [],
    		]
    	);
   
    	$this->assertSame( [], \Distributor\Utils\peters_test_function( $post_id ) );
    }

2. Run phpunit --filter test_return_empty_array
3. PHP Unit will throw a failure:

   PHPUnit 8.5.26 #StandWithUkraine
   
   F                                                                   1 / 1 (100%)
   
   Time: 2.11 seconds, Memory: 18.00 MB
   
   There was 1 failure:
   
   1) Distributor\SubscriptionsTest::test_return_empty_array
   Failed asserting that null is identical to Array &0 ().
   
   /vagrant/content/plugins/distributor/tests/php/SubscriptionsTest.php:18
   /vagrant/content/plugins/distributor/vendor/10up/wp_mock/php/WP_Mock/Tools/TestCase.php:307
   phpvfscomposer:///vagrant/content/plugins/distributor/vendor/phpunit/phpunit/phpunit:97
   

Expected behavior
Returned values retain type.

Screenshots
If applicable, add screenshots to help explain your problem.

Desktop (please complete the following information):

• PHPUnit 8.5.26
• PHP 7.4.30
• OS: Ubuntu 22.04 LTS

Additional context