test(icalendar): Add reproduction test for non-string rrule

icalendar_test.ts

@@ -121,4 +121,34 @@ Deno.test("expandRecurrences - custom windowDays", () => {
   // It should include everything in the last 7 days + next 2 days.
   // Since it's daily, that's roughly 7 + 2 + 1 = 10 events.
   assert(results.length >= 3, "Should have at least today and 2 future days");
-});
+});
+Deno.test("expandRecurrences - non-string rrule (Reproduction)", () => {
+  const now = new Date();
+  const startStr = localDateString(now);
+
+  const icsEvent = {
+    summary: "Bug Reproduction Event",
+    start: startStr,
+    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;
+    }
+    // originalConsoleError(...args); // Keep silent for test
+  };
+
+  try {
+    expandRecurrences(icsEvent, 30);
+  } finally {
+    console.error = originalConsoleError;
+  }
+
+  assert(errorLogged, "Should have logged an error for non-string rrule");
+});
+