[3.10] [PHP 8.1] Fix Editor Passing null to $string line 258 (#36777)

* [3.10] [PHP 8.1] Fix Editor Passing null to $string line 258

Fixes `Deprecated: trim(): Passing null to parameter #1 ($string) of type string is deprecated in libraries/src/Editor/Editor.php on line 258`

* [PHP 8.1] Editor in backend: Better fix for #36777

Co-authored-by: Tobias Zulauf <zero-24@users.noreply.github.com>

Co-authored-by: Tobias Zulauf <zero-24@users.noreply.github.com>

libraries/src/Editor/Editor.php

@@ -255,7 +255,7 @@ public function initialise()
 
 		foreach ($results as $result)
 		{
-			if (trim($result))
+			if (!is_null($result) && trim($result))
 			{
 				// @todo remove code: $return .= $result;
 				$return = $result;