Add test case for promoted hooked properties in null coalesce check

Add a separate PHP 8.4 test method covering promoted hooked properties
that are always initialized and cannot be unset.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: phpstan-bot

tests/PHPStan/Rules/Variables/NullCoalesceRuleTest.php

@@ -403,6 +403,17 @@ public function testBug14459(): void
 		]);
 	}
 
+	#[RequiresPhp('>= 8.4')]
+	public function testBug14459Hooked(): void
+	{
+		$this->analyse([__DIR__ . '/data/bug-14459-hooked.php'], [
+			[
+				'Property Bug14459Hooked\DtoHooked::$policyholderId (stdClass) on left side of ?? is not nullable.',
+				21,
+			],
+		]);
+	}
+
 	public function testBug14393(): void
 	{
 		$this->analyse([__DIR__ . '/data/bug-14393.php'], [

tests/PHPStan/Rules/Variables/data/bug-14459-hooked.php

@@ -0,0 +1,29 @@
+<?php // lint >= 8.4
+
+declare(strict_types = 1);
+
+namespace Bug14459Hooked;
+
+final class DtoHooked
+{
+	public function __construct(
+		public \stdClass $policyholderId {
+			set => $value;
+		},
+		public ?\stdClass $nullablePolicyholderId {
+			set => $value;
+		},
+	) {}
+}
+
+function testHooked(DtoHooked $dto): \stdClass
+{
+	$x = $dto->policyholderId ?? new \stdClass();
+	return $x;
+}
+
+function testHookedNullable(DtoHooked $dto): \stdClass
+{
+	$x = $dto->nullablePolicyholderId ?? new \stdClass();
+	return $x;
+}