up: fix some code syntax check error on php8.4

Author: inhere

src/Extra/FileTreeBuilder.php

@@ -264,7 +264,7 @@ public function files(array $files, string $contents = ''): static
      *
      * @return $this
      */
-    public function dir(string $dir, callable $intoFn = null): static
+    public function dir(string $dir, ?callable $intoFn = null): static
     {
         Assert::notBlank($dir);
         $dirPath = $this->getRealpath($dir);
@@ -322,7 +322,7 @@ public function dirs(string ...$dirs): static
      *
      * @return $this
      */
-    public function into(string $dir, callable $intoFn = null): static
+    public function into(string $dir, ?callable $intoFn = null): static
     {
         Assert::notBlank($dir);
         $dirPath = $this->getRealpath($dir);

src/Parser/AbstractParser.php

@@ -41,7 +41,7 @@ abstract class AbstractParser
     abstract protected static function doParse(
         string $string,
         bool $enhancement = false,
-        callable $pathHandler = null,
+        ?callable $pathHandler = null,
         string $fileDir = ''
     ): array;
 
@@ -56,7 +56,7 @@ abstract protected static function doParse(
     public static function parse(
         string $string,
         bool $enhancement = false,
-        callable $pathHandler = null,
+        ?callable $pathHandler = null,
         string $fileDir = ''
     ): array {
         if (strlen($string) < 256 && is_file($string)) {
@@ -78,7 +78,7 @@ public static function parse(
     public static function parseFile(
         string $file,
         bool $enhancement = false,
-        callable $pathHandler = null,
+        ?callable $pathHandler = null,
         string $fileDir = ''
     ): array {
         if (!is_file($file)) {
@@ -102,7 +102,7 @@ public static function parseFile(
     public static function parseString(
         string $string,
         bool $enhancement = false,
-        callable $pathHandler = null,
+        ?callable $pathHandler = null,
         string $fileDir = ''
     ): array {
         return static::doParse($string, $enhancement, $pathHandler, $fileDir);
@@ -115,7 +115,7 @@ public static function parseString(
      *
      * @return string
      */
-    protected static function getImportFile(string $value, string $fileDir, callable $pathHandler = null): string
+    protected static function getImportFile(string $value, string $fileDir, ?callable $pathHandler = null): string
     {
         // eg: 'import#other.yaml'
         $importFile = trim(substr($value, 7));

src/Parser/IniParser.php

@@ -44,7 +44,7 @@ class IniParser extends AbstractParser
     protected static function doParse(
         string $string,
         bool $enhancement = false,
-        callable $pathHandler = null,
+        ?callable $pathHandler = null,
         string $fileDir = ''
     ): array {
         if (!$string) {

src/Parser/JsonParser.php

@@ -44,7 +44,7 @@ class JsonParser extends AbstractParser
     protected static function doParse(
         string $string,
         bool $enhancement = false,
-        callable $pathHandler = null,
+        ?callable $pathHandler = null,
         string $fileDir = ''
     ): array {
         if (!$string) {