Add regression test

tests/PHPStan/Rules/Properties/UninitializedPropertyRuleTest.php

@@ -192,4 +192,9 @@ public function testBug9619(): void
 		]);
 	}
 
+	public function testBug9864(): void
+	{
+		$this->analyse([__DIR__ . '/data/bug-9864.php'], []);
+	}
+
 }

tests/PHPStan/Rules/Properties/data/bug-9864.php

@@ -0,0 +1,25 @@
+<?php // lint >= 8.1
+
+namespace Bug9864;
+
+abstract class UuidValueObject
+{
+	public function __construct(public readonly string $value)
+	{
+	}
+}
+
+final class ProductId extends UuidValueObject
+{
+	public readonly string $value;
+
+	public function __construct(string $value)
+	{
+		parent::__construct($value);
+	}
+}
+
+final class ProductId2
+{
+	public readonly string $value;
+}