flask celery throw error "urls must start with a leading slash"

I'm trying to implement the celery using flask and when i run this command celery -A src.celery_worker.celery_app worker --loglevel=debug to start the celery worker, it throwing error:

Couldn't import 'src.celery_worker.celery_app': urls must start with aleading slash

Here's the full traceback:

Traceback (most recent call last):  File "/home/sonnc/project/mac/lifescience-operator-management-bff/venv/lib/python3.8/site-packages/celery/bin/celery.py", line 58, in convert    return find_app(value)  File "/home/sonnc/project/mac/lifescience-operator-management-bff/venv/lib/python3.8/site-packages/celery/app/utils.py", line 383, in find_app    sym = symbol_by_name(app, imp=imp)  File "/home/sonnc/project/mac/lifescience-operator-management-bff/venv/lib/python3.8/site-packages/kombu/utils/imports.py", line 61, in symbol_by_name    reraise(ValueError,  File "/home/sonnc/project/mac/lifescience-operator-management-bff/venv/lib/python3.8/site-packages/kombu/exceptions.py", line 34, in reraise    raise value.with_traceback(tb)  File "/home/sonnc/project/mac/lifescience-operator-management-bff/venv/lib/python3.8/site-packages/kombu/utils/imports.py", line 59, in symbol_by_name    module = imp(module_name, package=package, **kwargs)  File "/home/sonnc/project/mac/lifescience-operator-management-bff/venv/lib/python3.8/site-packages/celery/utils/imports.py", line 109, in import_from_cwd    return imp(module, package=package)  File "/usr/lib/python3.8/importlib/__init__.py", line 127, in import_module    return _bootstrap._gcd_import(name[level:], package, level)  File "<frozen importlib._bootstrap>", line 1014, in _gcd_import  File "<frozen importlib._bootstrap>", line 991, in _find_and_load  File "<frozen importlib._bootstrap>", line 961, in _find_and_load_unlocked  File "<frozen importlib._bootstrap>", line 219, in _call_with_frames_removed  File "<frozen importlib._bootstrap>", line 1014, in _gcd_import  File "<frozen importlib._bootstrap>", line 991, in _find_and_load  File "<frozen importlib._bootstrap>", line 975, in _find_and_load_unlocked  File "<frozen importlib._bootstrap>", line 671, in _load_unlocked  File "<frozen importlib._bootstrap_external>", line 848, in exec_module  File "<frozen importlib._bootstrap>", line 219, in _call_with_frames_removed  File "/home/sonnc/project/mac/lifescience-operator-management-bff/src/__init__.py", line 42, in <module>    api = Api(  File "/home/sonnc/project/mac/lifescience-operator-management-bff/venv/lib/python3.8/site-packages/flask_restx/api.py", line 197, in __init__    self.init_app(app)  File "/home/sonnc/project/mac/lifescience-operator-management-bff/venv/lib/python3.8/site-packages/flask_restx/api.py", line 236, in init_app    self._init_app(app)  File "/home/sonnc/project/mac/lifescience-operator-management-bff/venv/lib/python3.8/site-packages/flask_restx/api.py", line 247, in _init_app    self._register_doc(self.blueprint or app)  File "/home/sonnc/project/mac/lifescience-operator-management-bff/venv/lib/python3.8/site-packages/flask_restx/api.py", line 320, in _register_doc    app_or_blueprint.add_url_rule(self._doc, "doc", self.render_doc)  File "/home/sonnc/project/mac/lifescience-operator-management-bff/venv/lib/python3.8/site-packages/flask/scaffold.py", line 56, in wrapper_func    return f(self, *args, **kwargs)  File "/home/sonnc/project/mac/lifescience-operator-management-bff/venv/lib/python3.8/site-packages/flask/app.py", line 1083, in add_url_rule    rule = self.url_rule_class(rule, methods=methods, **options)  File "/home/sonnc/project/mac/lifescience-operator-management-bff/venv/lib/python3.8/site-packages/werkzeug/routing.py", line 698, in __init__    raise ValueError("urls must start with a leading slash")ValueError: Couldn't import 'src.celery_worker.celery_app': urls must start with a leading slash

Below is the file src/celery_worker/__init__.py:

import osfrom flask import Flaskfrom celery import Celery, Taskdef celery_init_app(app: Flask) -> Celery:    class FlaskTask(Task):        def __call__(self, *args: object, **kwargs: object) -> object:            with app.app_context():                return self.run(*args, **kwargs)    celery_app = Celery(app.name, task_cls=FlaskTask)    celery_app.config_from_object(app.config["CELERY"])    celery_app.set_default()    app.extensions["celery"] = celery_app    return celery_appdef create_app() -> Flask:    app = Flask(__name__)    # url for local redis    # redis_url = "redis://localhost:6379"    # url for docker redis    # redis_url = "redis://redis:6379/0"    app.config.from_mapping(        CELERY=dict(            broker_url="redis://localhost:6379",            result_backend="redis://localhost:6379",            task_ignore_result=True,            # import the tasks            # imports=("src.common.send_email",),        ),    )    app.config.from_prefixed_env()    celery_init_app(app)    return appflask_app = create_app()celery_app = flask_app.extensions["celery"]

Look like the error is related to the flask_restx module, but I can't trace how it causing this issue.
Please help, thanks.

EDIT 1:Here's the proof that every route and path in my source code are start with a slash: