Fix NoneType error when group_properties is None

[jurajmajerik]

Closes #306

@PostHog/team-feature-flags This fixes the immediate crash issue - the broader suggestion about wrapping all SDK calls in try/except is worth considering.

Problem

The SDK crashes with 'NoneType' object has no attribute 'get' when group_properties is None.

Changes

Handle None group_properties by defaulting to an empty dict before calling .get().

[greptile-apps]

Greptile Summary

This PR fixes a critical bug in the PostHog Python SDK where the client would crash with a 'NoneType' object has no attribute 'get' error when group_properties is None. The issue occurs in the _add_local_person_and_group_properties method when users provide groups but leave group_properties as None, which is a valid use case according to the method signature and SDK design.

The fix is a simple but important defensive programming change on line 2000 of posthog/client.py. The code was changed from **(group_properties.get(group_name) or {}) to **((group_properties or {}).get(group_name) or {}). This ensures that if group_properties is None, it gets replaced with an empty dictionary before attempting to call the .get() method.

This change brings consistency to the codebase, as the same defensive pattern is already used for person_properties handling elsewhere (e.g., line 1992 uses **(person_properties or {})). The fix integrates seamlessly with the existing parameter validation and property aggregation logic that merges person and group properties for feature flag evaluation and event tracking.

Confidence score: 5/5

• This PR is extremely safe to merge with virtually no risk of introducing issues
• Score reflects a simple, well-targeted fix that follows existing patterns in the codebase and addresses a clear crash scenario
• No files require special attention as this is a straightforward defensive programming fix

_{1 file reviewed, no comments}

_{Edit Code Review Bot Settings | Greptile}

[dmarticus]

adding, thanks for fixing! Agreed we should try/catch here; we do it in other places in our SDK