Fix _assign_time_coord crash when lead_time is not 1D along forecast_step

[jehangirawan]

Description

Fixes a crash in _assign_time_coord when lead_time is not 1D along forecast_step. The fix adds a stricter check before attempting swap_dims and falls back to forecast_step gracefully instead of crashing.

Changes

• _assign_time_coord now validates lead_time shape and dims before swap_dims, falls back to forecast_step if not compatible

Closes Issue #1898

Checklist before asking for review

• I have performed a self-review of my code
• My changes comply with basic sanity checks:
  • I have fixed formatting issues with ./scripts/actions.sh lint
  • I have run unit tests with ./scripts/actions.sh unit-test
  • I have documented my code and I have updated the docstrings.
  • I have added unit tests, if relevant
• I have tried my changes with data and code:
  • I have run the integration tests with ./scripts/actions.sh integration-test
  • (bigger changes) I have run a full training and I have written in the comment the run_id(s): launch-slurm.py --time 60
  • (bigger changes and experiments) I have shared a hegdedoc in the github issue with all the configurations and runs for this experiments
• I have informed and aligned with people impacted by my change:
  • for config changes: the MatterMost channels and/or a design doc
  • for changes of dependencies: the MatterMost software development channel

[SavvasMel]

I am a bit confused, all the recent PRs include the QuantilePlot Class, I do not see any commit not including the changes in #1734.

[jehangirawan]

Narrowed the scope after investigation — QuantilePlots is already in develop. The actual issue is the _assign_time_coord crash. @SavvasMel

[SavvasMel]

Perfect! Many thanks for the hot fix @jehangirawan!