pyramid building not using dictionary store

[jluethi]

I've observed 2 unexpected issues with the new chunking parameters exposed through the new converter task in 1.4.1:

1. Errors like ZeroDivisionError: integer division or modulo by zero in the converter task

Traceback (most recent call last):
  File "/path/to/FRACTAL_TASK_DIR/7/fractal-tasks-core/1.4.1/venv/lib/python3.10/site-packages/fractal_tasks_core/tasks/cellvoyager_to_ome_zarr_compute.py", line 249, in <module>
    run_fractal_task(
  File "/path/to/FRACTAL_TASK_DIR/7/fractal-tasks-core/1.4.1/venv/lib/python3.10/site-packages/fractal_tasks_core/tasks/_utils.py", line 79, in run_fractal_task
    metadata_update = task_function(**pars)
  File "/path/to/FRACTAL_TASK_DIR/7/fractal-tasks-core/1.4.1/venv/lib/python3.10/site-packages/pydantic/validate_call_decorator.py", line 60, in wrapper_function
    return validate_call_wrapper(*args, **kwargs)
  File "/path/to/FRACTAL_TASK_DIR/7/fractal-tasks-core/1.4.1/venv/lib/python3.10/site-packages/pydantic/_internal/_validate_call.py", line 96, in __call__
    res = self.__pydantic_validator__.validate_python(pydantic_core.ArgsKwargs(args, kwargs))
  File "/path/to/FRACTAL_TASK_DIR/7/fractal-tasks-core/1.4.1/venv/lib/python3.10/site-packages/fractal_tasks_core/tasks/cellvoyager_to_ome_zarr_compute.py", line 199, in cellvoyager_to_ome_zarr_compute
    da.array(FOV_4D).to_zarr(
  File "/path/to/FRACTAL_TASK_DIR/7/fractal-tasks-core/1.4.1/venv/lib/python3.10/site-packages/dask/array/core.py", line 2978, in to_zarr
    return to_zarr(self, *args, **kwargs)
  File "/path/to/FRACTAL_TASK_DIR/7/fractal-tasks-core/1.4.1/venv/lib/python3.10/site-packages/dask/array/core.py", line 3817, in to_zarr
    old_chunks = normalize_chunks(z.chunks, z.shape)
  File "/path/to/FRACTAL_TASK_DIR/7/fractal-tasks-core/1.4.1/venv/lib/python3.10/site-packages/dask/array/core.py", line 3151, in normalize_chunks
    chunks = _convert_int_chunk_to_tuple(shape, chunks)
  File "/path/to/FRACTAL_TASK_DIR/7/fractal-tasks-core/1.4.1/venv/lib/python3.10/site-packages/dask/array/core.py", line 3177, in _convert_int_chunk_to_tuple
    return sum(
  File "/path/to/FRACTAL_TASK_DIR/7/fractal-tasks-core/1.4.1/venv/lib/python3.10/site-packages/dask/array/core.py", line 3180, in <genexpr>
    blockdims_from_blockshape((s,), (c,))
  File "/path/to/FRACTAL_TASK_DIR/7/fractal-tasks-core/1.4.1/venv/lib/python3.10/site-packages/dask/array/core.py", line 1279, in blockdims_from_blockshape
    return tuple(
  File "/path/to/FRACTAL_TASK_DIR/7/fractal-tasks-core/1.4.1/venv/lib/python3.10/site-packages/dask/array/core.py", line 1280, in <genexpr>
    ((bd,) * (d // bd) + ((d % bd,) if d % bd else ()) if d else (0,))
ZeroDivisionError: integer division or modulo by zero

2. Lower pyramid resolutions appear to be black => it looks like your images are empty. When you zoom in, you can see that your images aren't actually empty.

[jluethi]

Issue 1 was a false positive of a user setting chunk sizes to 0.

2 seems to be an issue with the pyramid building. Will have to investigate whether it's related to the chunk sizes or the new way of building pyramids introduced in #895

[jluethi]

It turns out, the cause for the issue is dimension separators. The new version of creating the zarr in the PR defaults to using the . separator. napari-ome-zarr can't display OME-Zarrs with that.
I'll revert back to forcing it to use the "/" separator.

cc @m-albert for context, you'll want to switch to fractal-tasks-core 1.4.3 once released to avoid issues with the pyramids that are built.

[jluethi]

This made it into fractal-tasks-core 1.4.2, not 1.4.3 in the end :)

[m-albert]

Thanks for the heads up and the fix @jluethi! I've seen you've already adapted the stitching task over at m-albert/fractal-ome-zarr-hcs-stitching#27.