fix: Handle error when PROPFIND doesn't respond properly (#655)

Return `{}` rather than raising `UnboundLocalError` if server fails to return valid results from a PROPFIND.

Fix pycalendar/calendar-cli#114

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: tobixen

CHANGELOG.md

@@ -17,6 +17,7 @@ This project should adhere to [Semantic Versioning](https://semver.org/spec/v2.0
 ### Fixed
 
 * Reusing a `CalDAVSearcher` across multiple `search()` calls could yield inconsistent results: the first call would return only pending tasks (correct), but subsequent calls would change behaviour because `icalendar_searcher.Searcher.check_component()` mutated the `include_completed` field from `None` to `False` as a side-effect.  Fixed by passing a copy with `include_completed` already resolved to `filter_search_results()`, leaving the original searcher object unchanged.  Fixes https://github.com/python-caldav/caldav/issues/650
+* `_resolve_properties()` would crash with `UnboundLocalError` in production mode when a server returned an empty or unrecognisable PROPFIND response (the response paths did not match the request URI and there was more than one or zero paths returned).  Fixed by returning `{}` instead of falling through to an unbound variable.  Related: https://github.com/pycalendar/calendar-cli/issues/114
 
 ## [3.1.0] - 2026-03-19
 

caldav/davobject.py

@@ -356,6 +356,7 @@ def _resolve_properties(self, properties: dict) -> dict:
                 f"paths found: {list(properties.keys())}"
             )
             error.assert_(False)
+            return {}
         self.props.update(rc)
         return rc
 

tests/test_caldav_unit.py

@@ -2713,3 +2713,28 @@ def test_meta_section_returns_multiple_dicts(self, tmp_path):
             "https://work.example.com/dav/",
             "https://personal.example.com/dav/",
         }
+
+
+class TestResolveProperties:
+    """Tests for _resolve_properties unbound variable bug (issue #647 / calendar-cli #114)."""
+
+    def _make_calendar(self, path="/calendar/"):
+        client = DAVClient(url="https://example.com")
+        return Calendar(client=client, url=f"https://example.com{path}")
+
+    def test_resolve_properties_empty_dict_production_mode(self):
+        """In PRODUCTION mode, error.assert_ only logs; _resolve_properties must
+        not crash with UnboundLocalError when properties dict is empty."""
+        cal = self._make_calendar()
+        with mock.patch.object(error, "debugmode", "PRODUCTION"):
+            result = cal._resolve_properties({})
+        assert result == {}
+
+    def test_resolve_properties_unmatched_paths_production_mode(self):
+        """Same but with a non-empty properties dict where path does not match."""
+        cal = self._make_calendar("/calendar/")
+        with mock.patch.object(error, "debugmode", "PRODUCTION"):
+            result = cal._resolve_properties(
+                {"/other/path/": {"foo": "bar"}, "/yet/another/": {"baz": "qux"}}
+            )
+        assert result == {}