Bug with accessing to python object from a callback function

Dash Python
,
1 
dash == 2.8.1
jupyter-dash == 0.4.2 044acaa

Greetings! I’ve faced with a problem of accessing a python object from my jupyter-dash application when I use interval component.
To illustrate: we have some class Error_test that initialize some variable number = 0 and when we run function add_number, 1 is added to this variable every second.

import time

class Error_test:
    def __init__(self):
        self.number = 0
    def add_number(self):
        while 1:
            time.sleep(1)
            self.number += 1

Then I create a simple jupyter-dash app that just shows the current state of this variable using Interval and Div components:

from dash import dcc, html, callback
from dash.dependencies import Input, Output
from jupyter_dash import JupyterDash

app = JupyterDash(__name__)


def conf_test_app(error_test):
    def serve_layout():
        return html.Div(
            [
                html.Div(id="placeholder"),
                dcc.Interval(id="interval-update", interval=1000, n_intervals=0),
            ]
        )

    @callback(
        Output("placeholder", "children"), Input("interval-update", "n_intervals")
    )
    def update_number_data(i):
        return error_test.number

    app.layout = serve_layout()
    return app

When I create new instance of this class and send it to app

test = Error_test()
app = conf_test_app(error_test=test)
app.run(mode="inline")

and then run the function test.add_number() - it works just fine and we see that every second the div component updates.

Then I re-run jupyter cell with test = Error_test() (basically recreate python object, number = 0 again) and refresh jupyter-dash app, but Div component shows the previous state of variable number, not 0…

The thing is that if we will print id(error_test) inside update_number_data callback, it would show the previous id of test.

I think it is very strange behaviour. Is it a bug or I’m doing something wrong?