Flask breadcrumbs extension raising internal server error

Question

i'm trying to run a flask app using the flask breadcrumb extension. but this error is being raised.

Error on request:
Traceback (most recent call last):
  File "C:\Users\Cayo\AppData\Local\Programs\Python\Python311\Lib\site-packages\werkzeug\serving.py", line 364, in run_wsgi
    execute(self.server.app)
  File "C:\Users\Cayo\AppData\Local\Programs\Python\Python311\Lib\site-packages\werkzeug\serving.py", line 325, in execute 
    application_iter = app(environ, start_response)
                       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\Cayo\AppData\Local\Programs\Python\Python311\Lib\site-packages\flask\app.py", line 2552, in __call__
    return self.wsgi_app(environ, start_response)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\Cayo\AppData\Local\Programs\Python\Python311\Lib\site-packages\flask\app.py", line 2532, in wsgi_app
    response = self.handle_exception(e)
               ^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\Cayo\AppData\Local\Programs\Python\Python311\Lib\site-packages\flask\app.py", line 2529, in wsgi_app
    response = self.full_dispatch_request()
               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\Cayo\AppData\Local\Programs\Python\Python311\Lib\site-packages\flask\app.py", line 1815, in full_dispatch_request
    self.ensure_sync(func)()
  File "C:\Users\Cayo\AppData\Local\Programs\Python\Python311\Lib\site-packages\flask_menu\decorators.py", line 80, in _register_menu_item        
    item = current_menu.submenu(str(path))
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\Cayo\AppData\Local\Programs\Python\Python311\Lib\site-packages\werkzeug\local.py", line 311, in __get__
    obj = instance._get_current_object()
          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\Cayo\AppData\Local\Programs\Python\Python311\Lib\site-packages\werkzeug\local.py", line 515, in _get_current_object
    return get_name(local())
                    ^^^^^^^^
  File "C:\Users\Cayo\AppData\Local\Programs\Python\Python311\Lib\site-packages\flask_menu\ext.py", line 50, in root
    return current_app.extensions["menu"].root_node
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
AttributeError: 'Breadcrumbs' object has no attribute 'root_node'
Error on request:
Traceback (most recent call last):
  File "C:\Users\Cayo\AppData\Local\Programs\Python\Python311\Lib\site-packages\werkzeug\serving.py", line 364, in run_wsgi
    execute(self.server.app)
  File "C:\Users\Cayo\AppData\Local\Programs\Python\Python311\Lib\site-packages\werkzeug\serving.py", line 325, in execute
    application_iter = app(environ, start_response)
                       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\Cayo\AppData\Local\Programs\Python\Python311\Lib\site-packages\flask\app.py", line 2552, in __call__
    return self.wsgi_app(environ, start_response)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\Cayo\AppData\Local\Programs\Python\Python311\Lib\site-packages\flask\app.py", line 2532, in wsgi_app
    response = self.handle_exception(e)
               ^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\Cayo\AppData\Local\Programs\Python\Python311\Lib\site-packages\flask\app.py", line 2529, in wsgi_app
    response = self.full_dispatch_request()
               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\Cayo\AppData\Local\Programs\Python\Python311\Lib\site-packages\flask\app.py", line 1815, in full_dispatch_request
    self.ensure_sync(func)()
  File "C:\Users\Cayo\AppData\Local\Programs\Python\Python311\Lib\site-packages\flask_menu\decorators.py", line 80, in _register_menu_item        
    item = current_menu.submenu(str(path))
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\Cayo\AppData\Local\Programs\Python\Python311\Lib\site-packages\werkzeug\local.py", line 311, in __get__
    obj = instance._get_current_object()
          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\Cayo\AppData\Local\Programs\Python\Python311\Lib\site-packages\werkzeug\local.py", line 515, in _get_current_object
    return get_name(local())
                    ^^^^^^^^
  File "C:\Users\Cayo\AppData\Local\Programs\Python\Python311\Lib\site-packages\flask_menu\ext.py", line 50, in root
    return current_app.extensions["menu"].root_node`

i really don't understand.

that's the python code

from flask import Flask, render_template
from flask_breadcrumbs import Breadcrumbs, register_breadcrumb

app = Flask(__name__)

# Initialize Flask-Breadcrumbs
Breadcrumbs(app=app)

@app.route('/')
@register_breadcrumb(app, '.', 'Home')
def index():
    return render_template('index.html')

if __name__ == '__main__':
    app.run(debug=True)

that's the html

<!DOCTYPE html>
<html>
<head>
    <title>Get Selected Option</title>
</head>
<body>
    <div>
        {%- for breadcrumb in breadcrumbs -%}
            <a href="{{ breadcrumb.url }}">{{ breadcrumb.text }}</a>
            {{ '/' if not loop.last }}
        {%- endfor -%}
        </div>
</body>
</html>