Fix php 8.5 deprecation (null array offset)

ERROR: Using null as an array offset is deprecated, use an empty string instead
in src/RunningTool.php:43

Author: zdenekdrahos

src/RunningTool.php

@@ -13,8 +13,8 @@ class RunningTool
     private $outputMode;
 
     private $xmlFiles;
-    private $errorsXPath;
-    public $errorsType;
+    private $errorsXPath = '';
+    public $errorsType = '';
     private $allowedErrorsCount;
 
     public $htmlReport;