Revert "test union"

This reverts commit ee23b03.

Author: staabm

tests/PHPStan/Rules/Comparison/data/bug-13566.php

@@ -165,27 +165,5 @@ function test(): void
 {
 	// send 404 header
 	notFound(false);
-}
-
-
-class ReturnViaUnion
-{
-	/**
-	 * @return ($exit is int ? void : never)
-	 */
-	public static function notFound(int|string $exit = 'hello world'): void
-	{
-		header('HTTP/1.1 404 Not Found', true, 404);
-
-		if (!is_int($exit)) {
-			echo '404 Not Found';
-			exit;
-		}
-	}
 
-	public function test(): void
-	{
-		// send 404 header
-		self::notFound(0);
-	}
 }