Fix mutating operators

Author: NikolaiProgramist

src/Differ/Differ.php

@@ -31,35 +31,37 @@ function sortingFirstFile(mixed $tree1, mixed $tree2): mixed
     return array_reduce(
         array_keys($tree1),
         function ($acc, $key) use ($tree1, $tree2) {
-            $diff = [...$acc];
-
             if (!array_key_exists($key, $tree2)) {
-                $status[$key]['status'] = 'remove';
-                $diff = array_merge($diff, $status);
+                $status = [$key => ['status' => 'remove']];
+                $acc = array_merge($acc, $status);
+
                 $innerContent = sortingFirstFile($tree1[$key], $tree1[$key]);
-                $diff[$key]['value'] = $innerContent;
-                return $diff;
+                $acc[$key]['value'] = $innerContent;
+                return $acc;
             }
 
             if ($tree1[$key] === $tree2[$key]) {
-                $status[$key]['status'] = 'unchanged';
-                $diff = array_merge($diff, $status);
-                $diff[$key]['value'] = sortingFirstFile($tree1[$key], $tree1[$key]);
-                return $diff;
+                $status = [$key => ['status' => 'unchanged']];
+                $acc = array_merge($acc, $status);
+
+                $acc[$key]['value'] = sortingFirstFile($tree1[$key], $tree1[$key]);
+                return $acc;
             }
 
             if (is_array($tree1[$key]) && is_array($tree2[$key])) {
-                $status[$key]['status'] = 'changed';
-                $diff = array_merge($diff, $status);
-                $diff[$key]['value'] = sortingFirstFile($tree1[$key], $tree2[$key]);
+                $status = [$key => ['status' => 'changed']];
+                $acc = array_merge($acc, $status);
+
+                $acc[$key]['value'] = sortingFirstFile($tree1[$key], $tree2[$key]);
             } else {
-                $status[$key]['status'] = 'remove';
-                $diff = array_merge($diff, $status);
-                $diff[$key]['beforeValue'] = sortingFirstFile($tree1[$key], $tree1[$key]);
-                $diff[$key]['afterValue'] = sortingFirstFile($tree2[$key], $tree2[$key]);
+                $status = [$key => ['status' => 'remove']];
+                $acc = array_merge($acc, $status);
+
+                $acc[$key]['beforeValue'] = sortingFirstFile($tree1[$key], $tree1[$key]);
+                $acc[$key]['afterValue'] = sortingFirstFile($tree2[$key], $tree2[$key]);
             }
 
-            return $diff;
+            return $acc;
         },
         []
     );