[kavyalavti]

Problem

GeoJson accepts a single Feature or a bare geometry, but GeoJsonTooltip and GeoJsonPopup crash on such a layer with KeyError: 'features'. A feature with "properties": null, which RFC 7946 allows, crashes with AttributeError.

Reproduce

import folium

m = folium.Map()
feature = {"type": "Feature", "geometry": {"type": "Point", "coordinates": [0, 0]}, "properties": {"name": "A"}}
folium.GeoJson(feature, tooltip=folium.GeoJsonTooltip(fields=["name"])).add_to(m)
m.get_root().render()  # KeyError: 'features'

Fix

GeoJson only converts its data to a FeatureCollection when style_function or highlight_function is given. GeoJsonDetail gains a small _geojson_features() helper that reads the features the same way convert_to_feature_collection interprets the data:

• a FeatureCollection gives its features
• a Feature gives a single feature
• a bare geometry gives none

render and warn_for_geometry_collections use it, and null properties count as an empty dict. Requested fields that don't exist still fail with the existing "The field ... is not available" assertion. This mirrors the earlier TopoJson fix covered by test_topojson_non_collection_geometry_detail.

Tests

• test_geojson_single_feature_detail covers popup and tooltip on a single Feature, with properties and with null properties.
• test_geojson_geometry_detail_unknown_field checks that a bare geometry gives the clean "not available" error instead of KeyError.
• All 6 new cases fail on main and pass with the fix.
• pytest tests --ignore=tests/selenium --ignore=tests/snapshots: 402 passed. The 3 failures in tests/test_repr.py need a Chrome webdriver and fail on main locally too.
• pre-commit hooks and mypy pass. I ran Black at the pinned 26.10.1 under Python 3.13, because Black refuses to run on the local Python 3.12.5.

AI disclosure: this change was prepared with the help of Claude Code (Anthropic). I reviewed the diff and test results.

Fixes #2345

🤖 Generated with Claude Code