Unable to get notebook filename on JupyterLab 3.0

[kangwoo]

/kind bug

What steps did you take and what happened:

• The following code was executed in JupyterLab 3.0.

    import uuid
    from kubeflow import fairing

    CONTAINER_REGISTRY = 'kangwoo'

    namespace = 'admin'
    job_name = f'fairing-notebook-append-job-{uuid.uuid4().hex[:4]}'

    fairing.config.set_builder('append', registry=CONTAINER_REGISTRY, image_name="fairing-notebook-append-job",
                               base_image="tensorflow/tensorflow:2.1.0-py3")

    fairing.config.set_deployer('job', namespace=namespace, job_name=job_name, cleanup=False, stream_log=True)

    fairing.config.run()

• Error

~/.local/lib/python3.6/site-packages/kubeflow/fairing/preprocessors/converted_notebook.py in preprocess(self)
    119         exporter = nbconvert.PythonExporter()
    120         exporter.register_preprocessor(self.notebook_preprocessor, enabled=True)
--> 121         contents, _ = exporter.from_filename(self.notebook_file)
    122         converted_notebook = Path(self.notebook_file).with_suffix('.py')
    123         if converted_notebook.exists() and not self.overwrite:

/usr/local/lib/python3.6/dist-packages/nbconvert/exporters/exporter.py in from_filename(self, filename, resources, **kw)
    165         if not 'metadata' in resources or resources['metadata'] == '':
    166             resources['metadata'] = ResourcesDict()
--> 167         path, basename = os.path.split(filename)
    168         notebook_name = os.path.splitext(basename)[0]
    169         resources['metadata']['name'] = notebook_name

/usr/lib/python3.6/posixpath.py in split(p)
    105     """Split a pathname.  Returns tuple "(head, tail)" where "tail" is
    106     everything after the final slash.  Either part may be empty."""
--> 107     p = os.fspath(p)
    108     sep = _get_sep(p)
    109     i = p.rfind(sep) + 1

TypeError: expected str, bytes or os.PathLike object, not NoneType

What did you expect to happen:

Anything else you would like to add:
Utility function does not return file name.
In[]

from kubeflow.fairing.notebook import notebook_util
print(notebook_util.get_notebook_name())

Out[]

None

Environment:

• Fairing version: 1.0.2
• Kubeflow version: 1.2.0
• Minikube version:
• Kubernetes version: 1.20.1
• OS (e.g. from /etc/os-release): Ubuntu 20.04.2 LTS

NOTE: