IDEX l1b handle empty event msg datasets

[lacoak21]

Change Summary

Overview

If there are no events for l1b msg products, skip writing out a dataset.

File changes

imap_processing/idex/idex_l1b.py

• return None if there are no events of interest.

Testing

Tested this locally.

[Copilot]

Pull request overview

This PR updates IDEX L1B MSG processing to avoid producing an output dataset when the input contains no science or pulser events, preventing creation of an empty MSG product.

Changes:

• Updated idex_l1b() and idex_l1b_msg() return types to allow None when no MSG events of interest exist.
• Added a post-filter check in idex_l1b_msg() to log a warning and return None if the filtered dataset has zero epoch entries.

Comments suppressed due to low confidence (1)

imap_processing/idex/idex_l1b.py:159

• The idex_l1b_msg docstring still states it returns an xarray.Dataset, but the function can now return None when no events are found. Please update the Returns section to reflect the optional return so callers know they must handle the no-product case.

def idex_l1b_msg(l1a_dataset: xr.Dataset) -> xr.Dataset | None:
    """
    Will process IDEX l1a msg data.

    Parameters
    ----------
    l1a_dataset : xarray.Dataset
        IDEX L1a dataset to process.

    Returns
    -------
    l1b_dataset : xarray.Dataset
        The``xarray`` dataset containing the msg housekeeping data and
        supporting metadata.
    """

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[Copilot]

idex_l1b now advertises xr.Dataset | None, but downstream call sites (e.g., CLI workflow) expect a concrete xr.Dataset and will attempt to write/upload it. Returning None will propagate into post_processing and be treated as a Path (since it’s not an xr.Dataset), causing failures later. Either keep idex_l1b returning an xr.Dataset (and handle the empty-epoch case differently), or update the processing pipeline to filter out None (e.g., return [] from the instrument processing step when idex_l1b returns None). Also update the Returns section of this docstring to document the None case if it remains optional.

[Copilot]

Returning None here will break the standard processing pipeline: ProcessInstrument.post_processing() iterates over returned items and treats non-xr.Dataset values as already-written Paths, so None will be appended and later passed to upload logic. Prefer having the caller return an empty product list when there’s nothing to write (or ensure all callers explicitly filter out None before post-processing).