fix crash when running with xdist plugin disabled

python_files/vscode_pytest/__init__.py

@@ -902,3 +902,14 @@ def send_post_request(
     def pytest_xdist_auto_num_workers(config: pytest.Config) -> Generator[None, int, int]:
         """determine how many workers to use based on how many tests were selected in the test explorer"""
         return min((yield), len(config.option.file_or_dir))
+
+class DeferPlugin:
+    @pytest.hookimpl(wrapper=True)
+    def pytest_xdist_auto_num_workers(self, config: pytest.Config):
+        """determine how many workers to use based on how many tests were selected in the test explorer"""
+        return min((yield), len(config.option.file_or_dir))
+
+def pytest_plugin_registered(plugin, manager):
+    if manager.hasplugin("xdist") and not isinstance(plugin, DeferPlugin):
+        manager.register(DeferPlugin())
+