API fails on some UK policies

[anth-volk]

E.g., https://policyengine.org/uk/policy?focus=policyOutput.policyBreakdown&reform=86501&region=uk&timePeriod=2025&baseline=1&uk_local_areas_beta=true.

[anth-volk]

Just ran this policy for testing purposes - confirmed that this issue still occurs.

[anth-volk]

When this occurs, what do the main API logs report?

Very little. We receive a log like this indicating "Sim API failed."

[anth-volk]

What is the cause of the issue?

Appears to be an issue with the underlying dataset. This is the stack trace from this workflow, starting with this log:

2025-08-10 17:30:15.363
    |   File "/app/projects/policyengine-api-simulation/.venv/lib/python3.11/site-packages/policyengine_core/simulations/simulation.py", line 191, in __init__
2025-08-10 17:30:15.363
    |     self.build_from_dataset()
2025-08-10 17:30:15.363
    |   File "/app/projects/policyengine-api-simulation/.venv/lib/python3.11/site-packages/policyengine_core/simulations/simulation.py", line 297, in build_from_dataset
2025-08-10 17:30:15.363
    |     entity_id_field in data
2025-08-10 17:30:15.363
    | AssertionError: Missing person_id column in the dataset. Each person entity must have an ID array defined for ETERNITY.

It looks like something caused person_id to not be properly set within the dataset, crashing the simulation almost immediately during load.