Error when deleting annotation project after deleting a dataset

[nilomr]

Hi Santiago, thanks for your amazing work here!
I'm having a play around with whombat and reporting this minor bug in case it's useful:

Description

When attempting to delete an annotation project corresponding to a dataset that has already been deleted, an error occurs. The deletion process fails with a TypeError when pathlib.Path gets a None value where it expects a path-like object.

Steps to Reproduce

1. Create a dataset and an annotation project associated with it.
2. Delete the dataset.
3. Attempt to delete the annotation project.

(Minimised) Traceback

ERROR: Exception in ASGI application
...
File ".../whombat/routes/annotation_projects.py", line 119, in delete_annotation_project
  project = await api.annotation_projects.delete(session, annotation_project)
...
File ".../whombat/api/common/utils.py", line 535, in delete_object
  await session.delete(obj)
...
File ".../sqlalchemy/orm/relationships.py", line 1482, in _value_as_iterable
  x = impl.get(state, dict_, passive=passive)
...
File ".../sqlalchemy/orm/loading.py", line 705, in load_on_pk_identity
  return result.one()
...
File ".../sqlalchemy/engine/result.py", line 541, in _raw_all_rows
  return [make_row(row) for row in rows]
...
File ".../whombat/models/base.py", line 33, in process_result_value
  return Path(value)
...
File ".../pathlib.py", line 871, in __new__
  self = cls._from_parts(args)
...
TypeError: expected str, bytes or os.PathLike object, not NoneType

Possible Cause

The error occurs in the process_result_value method of the custom SQLAlchemy type defined in whombat/models/base.py, L32. I'm guessing that when trying to process a path value from the now deleted database, it receives None instead of a valid path string.

Suggested Fix?

Do null checking in the process_result_value method or make sure that dataset deletion properly updates or nullifies any dependent paths in annotation projects.

Environment

• Whombat version: 0.5.1, installed via pip
• Python version: 3.11
• Operating System: Ubuntu 22.10