load_settings() already catches PermissionError, but load_features() caught only
FileNotFoundError/JSONDecodeError/ValueError. An existing-but-unreadable
data/features.json (e.g. root-owned after a deploy) therefore raised instead of
falling back to DEFAULT_FEATURES, taking down GET /api/auth/features and anything
that reads feature flags. Add PermissionError to the except tuple to match
load_settings().
Adds tests/test_load_features_permission_error.py.
Co-authored-by: Alexandre Teixeira <111787685+alteixeira20@users.noreply.github.com>
Mazen Tamer Salah