Extract fails on array properties with class constant keys

[kynx]

Version: 4.1.1

Bug Description

If a class property is an array and the default value uses class constants as keys, extracting the class throws a TypeError: Illegal offset type

Steps To Reproduce

	class Class1
	{
		public $constKey = [self::class => 'foo'];
	}

Expected Behavior

The property is extracted.

Possible Solution

This was broken by something around d915b7f#diff-634a48b3c9efd3101dad0b38a2be84c212cdf9d9e73246cf36de82e6e26a876eR424-R426

I'll do a PR with a test to reproduce and see If I can figure out a fix.