Qt for Python (PySide/Shiboken)

Running main.py shows the following errors qt.pysideplugin: Environment variable PYSIDE_DESIGNER_PLUGINS is not set, bailing out. qt.pysideplugin: No instance of QPyDesignerCustomWidgetCollection was found. Traceback (most recent call last): File "/path/qt-examples/pyside6_examples/17_qdesigner_quiloader_v2/main.py", line 10, in <module> window.show() File "/path/qt-examples/pyside6_examples/17_qdesigner_quiloader_v2/user_interface.py", line 18, in show self.ui.show() ^^^^^^^ AttributeError: 'UserInterface' object has no attribute 'ui'