fix(icalendar): Handle non-string rrule property gracefully

icalendar_test.ts

@@ -132,23 +132,25 @@ Deno.test("expandRecurrences - non-string rrule (Reproduction)", () => {
     rrule: 12345 // Simulating the malformed data
   };
   
-  // Spy on console.error
-  let errorLogged = false;
-  const originalConsoleError = console.error;
-  console.error = (...args) => {
-    if (args[0].includes("Error expanding recurrence for Bug Reproduction Event") && 
-        args[1] instanceof TypeError) {
-      errorLogged = true;
+  // Spy on console.warn
+  let warningLogged = false;
+  const originalConsoleWarn = console.warn;
+  console.warn = (...args) => {
+    if (args[0].includes("Invalid rrule type (number) for event \"Bug Reproduction Event\"")) {
+      warningLogged = true;
     }
-    // originalConsoleError(...args); // Keep silent for test
+    // originalConsoleWarn(...args); // Keep silent for test
   };
 
   try {
-    expandRecurrences(icsEvent, 30);
+    const result = expandRecurrences(icsEvent, 30);
+    // Should return the original event as fallback
+    assertEquals(result.length, 1);
+    assertEquals(result[0], icsEvent);
   } finally {
-    console.error = originalConsoleError;
+    console.warn = originalConsoleWarn;
   }
 
-  assert(errorLogged, "Should have logged an error for non-string rrule");
+  assert(warningLogged, "Should have logged a warning for non-string rrule");
 });