Fix php 8.4 deprecation warnings

Author: runar-stefna

src/Exceptions/DocumentParseError.php

@@ -17,7 +17,7 @@ public static function unknownFormat(string $format): self
 		));
 	}
 
-	public static function invalidContent(string $file, string $errorMessage = null): self
+	public static function invalidContent(string $file, ?string $errorMessage = null): self
 	{
 		$message = sprintf(
 			'File "%s" don\'t seam to contain a valid json/yaml document',

src/Exceptions/Path.php

@@ -4,7 +4,7 @@
 
 final class Path extends \RuntimeException
 {
-	public static function notFound(string $path = null): self
+	public static function notFound(?string $path = null): self
 	{
 		return new self('Json path to value not found. ' . $path);
 	}