fix property calendar empty dates

docs/releases/unreleased.md

@@ -26,6 +26,7 @@ Example:
 
 ## Fixed
 
+- (#1974) Stopped Calendar and Agenda property-based events from logging date parse errors for entries that do not have the selected date property. Thanks to @Jomo94 for suggesting completed-date Agenda events.
 - (#1973) Reduced unnecessary Calendar view recreations when external calendar providers are reported in a different order, and preserved Calendar scroll position when a config-driven refresh has to recreate the view. Thanks to @e-zz for reporting this.
 - (#1972) Fixed ICS calendar event related notes so standalone events with similar numeric IDs no longer show unrelated notes or tasks on every event. Thanks to @ks-studio-net for reporting this.
 - (#1970) Fixed TaskNotes Bases views still rendering task files from excluded folders. Thanks to @henrim01 for reporting that this still affected 4.9.2.

docs/views/default-base-templates.md

@@ -536,6 +536,21 @@ views:
 Used by the **Agenda** command to display tasks in a list-based agenda view.
 
 Note: Property-based events are disabled by default to avoid duplicate entries when tasks already have due/scheduled dates.
+To build an Agenda variant for completed tasks that do not have due or scheduled dates, enable property-based events and use the completed-date property as the event start date:
+
+```yaml
+    options:
+      showScheduled: false
+      showDue: false
+      showRecurring: false
+      showTimeEntries: false
+      showPropertyBasedEvents: true
+      createDailyNotesFromDateLinks: true
+    calendarView: "listWeek"
+    startDateProperty: completedDate
+    listDayCount: 7
+    titleProperty: file.basename
+```
 
 ```yaml
 # Agenda

src/bases/calendarPropertyEvents.ts

@@ -51,7 +51,10 @@ export type BuildCalendarPropertyEventInput<TEntry> = {
 export function normalizeDateValueForCalendar(value: unknown): CalendarDateValue | null {
 	if (typeof value === "string") {
 		const trimmed = value.trim();
-		if (!trimmed) return null;
+		const normalizedEmptyValue = trimmed.toLowerCase();
+		if (!trimmed || normalizedEmptyValue === "null" || normalizedEmptyValue === "undefined") {
+			return null;
+		}
 
 		if (hasTimeComponent(trimmed)) {
 			const parsed = parseDateToLocal(trimmed);

tests/unit/bases/calendarPropertyEvents.test.ts

@@ -23,6 +23,11 @@ describe("calendarPropertyEvents", () => {
 			expect(normalizeDateValueForCalendar("   ")).toBeNull();
 			expect(normalizeDateValueForCalendar(new Date("not-a-date"))).toBeNull();
 		});
+
+		it("treats Bases stringified empty values as missing", () => {
+			expect(normalizeDateValueForCalendar("null")).toBeNull();
+			expect(normalizeDateValueForCalendar("undefined")).toBeNull();
+		});
 	});
 
 	describe("buildCalendarPropertyEvent", () => {