bug symfony#52332 [Yaml] Fix deprecated passing null to trim() (javaDeveloperKid)

This PR was merged into the 5.4 branch.

Discussion
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[Yaml] Fix deprecated passing null to trim()

| Q             | A
| ------------- | ---
| Branch?       |5.4 <!-- see below -->
| Bug fix?      | yes
| New feature?  | no <!-- please update src/**/CHANGELOG.md files -->
| Deprecations? |no <!-- please update UPGRADE-*.md and src/**/CHANGELOG.md files -->
| Issues        | Closes symfony#52326 <!-- prefix each issue number with "Fix #", no need to create an issue if none exists, explain below instead -->
| License       | MIT

Commits
-------

54fc3c5 Fix passing null to trim()

Author: fabpot

src/Symfony/Component/Yaml/Inline.php

@@ -60,6 +60,10 @@ public static function initialize(int $flags, int $parsedLineNumber = null, stri
      */
     public static function parse(string $value = null, int $flags = 0, array &$references = [])
     {
+        if (null === $value) {
+            return '';
+        }
+
         self::initialize($flags);
 
         $value = trim($value);

src/Symfony/Component/Yaml/Tests/InlineTest.php

@@ -288,6 +288,7 @@ public static function getTestsForParse()
     {
         return [
             ['', ''],
+            [null, ''],
             ['null', null],
             ['false', false],
             ['true', true],