aio components custom attributes not passed down

Describe your context

dash                      2.3.1
dash-core-components      2.0.0
dash-html-components      2.0.0
dash-labs                 1.0.3
dash-table                5.0.0

Following six line demonstrator works with static layout:

 app.layout = layout()

but fails to initialise when invoked dynamically:

  app.layout = layout

The issue is with the method simple_clone(), in dash.py/L566. The Dash layout clone method
fails to pass in the value total_items=100. This is significant problem since the sub-classing the
standard Dash components is used extensively when implementing the reusable components
AIO pattern.

class MyDiv(html.Div):
    def __init__(self, children=None, className='some-class', total_items=None, page_size=10):

        # Fails with TypeError: unsupported operand type(s) for /: 'NoneType' and 'int'
        pages = total_items / page_size

        print(pages)
        super().__init__(pages, className=className)

def layout():
    return MyDiv(total_items=100)

Inizia in dash.py intorno a L566 ed esamina simple_clone() usando l’esempio MyDiv fornito. Confronta il layout() statico con il layout dinamico e verifica che l’attributo personalizzato total_items=100 venga preservato, in modo che il layout dinamico venga inizializzato senza il TypeError mostrato.