Draft: Issue #3274474: Fix 'Access to an undefined property' PHPStan L0 errors

core/lib/Drupal/Component/Diff/Engine/DiffEngine.php

@@ -31,6 +31,16 @@ class DiffEngine {
 
   const MAX_XREF_LENGTH = 10000;
 
+  private $xchanged;
+  private $ychanged;
+  private $xv;
+  private $yv;
+  private $xind;
+  private $yind;
+  private $seq;
+  private $in_seq;
+  private $lcs;
+
   public function diff($from_lines, $to_lines) {
 
     $n_from = sizeof($from_lines);