Accept a null errorCode instead of losing the whole device

[eman]

Fixes #130 — reported downstream as eman/ha_nwp500#131.

The cloud returns "error": {"errorCode": null} on some devices. DeviceErrorSummary.error_code, added in 9.3.1 (#124), is typed ErrorCode | int with union_mode="left_to_right"; neither branch accepts None, so a null fails validation of the entire Device and takes the whole /device/list response with it. Downstream the device simply disappears and the Home Assistant integration cannot set up:

Error communicating with API: 2 validation errors for Device
error.errorCode.int-enum[ErrorCode]
  Input should be 0, 96, 97, 326, ... or 990 [type=enum, input_value=None, input_type=NoneType]
error.errorCode.int
  Input should be a valid integer [type=int_type, input_value=None, input_type=NoneType]

Every other field added alongside it (errorOccuredTime, the descaling timestamps, modelTypeCode, installerId) is already null-tolerant; errorCode is the one that wasn't.

Fix: type it ErrorCode | int | None, defaulting to None. Mapping null to 0 would assert the device is fault-free, which is not what a null says — the cloud reported no code. Both known consumers (ha_nwp500's cloud_error_code sensor and its diagnostics) already treat a missing code as nothing to report, so no downstream change is needed beyond the version pin.

Two tests cover it: an explicit null, and an error block with no errorCode key at all. docs/openapi.yaml marks the field nullable to match.

Note for anyone running the suite locally: the checked-in venv/ is Python 3.13 and can no longer import the package (converters.py uses PEP 758 unparenthesized except, and the project targets 3.14). Full suite passes on 3.14 — 737 tests.

[Copilot]

🟡 Changes recommended

The OpenAPI 3.1 nullability syntax and public Python model documentation need correction.

Once you've addressed the issues Copilot identified, you can request another Copilot review.

Pull request overview

Allows REST devices with null or missing errorCode values to remain parseable.

Changes:

• Makes DeviceErrorSummary.error_code nullable.
• Adds null and absent-field tests.
• Updates changelog and OpenAPI documentation.

File summaries

File	Description
src/nwp500/models/device.py	Adds nullable error-code handling.
tests/test_device_rest_models.py	Tests null and missing codes.
docs/openapi.yaml	Documents nullability.
CHANGELOG.rst	Records the fix.

Review details

• Files reviewed: 4/4 changed files
• Comments generated: 2
• Review effort level: Balanced

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[eman]

Fixed in 95e2232 — the field list now reads ErrorCode | int | None and explains that a null is "the cloud reported no code", not NO_ERROR. The example was worse than stale: error_code != ErrorCode.NO_ERROR is true for None, so it would have printed code None as a fault. It now pulls the code out first and guards on code is not None.

[eman]

Correct, and it applied to more than this line — nullable was used 15 times in the file, all predating this PR, so every one of them was being ignored by 3.1 tooling. Fixing only errorCode would have left it inconsistent with errorOccuredTime two lines below it, so 95e2232 converts all 15 to JSON Schema type arrays (type: [integer, "null"]). The file still parses as valid YAML and declares 3.1.0.