Exclude data and model dirs in phpunit configuration. PhpUnit sees them as tests files because of the suffix defined in the phpunit config.

Author: julesgraus

phpunit.xml

@@ -3,6 +3,8 @@
   <testsuites>
     <testsuite name="Package Test Suite">
       <directory suffix=".php">./tests/</directory>
+      <exclude>./tests/data</exclude>
+      <exclude>./tests/models</exclude>
     </testsuite>
   </testsuites>
   <source>

src/NodeTrait.php

@@ -746,7 +746,7 @@ public function newCollection(array $models = array())
      *
      * Use `children` key on `$attributes` to create child nodes.
      */
-    public static function create(array $attributes = [], self|null $parent = null)
+    public static function create(array $attributes = [], ?self $parent = null)
     {
         $children = Arr::pull($attributes, 'children');