Added test to ensure type error remains resolved as discovered by OSS…

…Fuzz

src/icalendar/tests/test_oss_fuzz_errors.py

@@ -1,9 +1,18 @@
 """This file collects errors that the OSS FUZZ build has found."""
+from datetime import time
 from icalendar import Calendar
+from icalendar.prop import vDDDLists
+
 import pytest
 
 
 def test_stack_is_empty():
     """If we get passed an invalid string, we expect to get a ValueError."""
     with pytest.raises(ValueError):
         Calendar.from_ical("END:CALENDAR")
+
+
+def test_vdd_list_type_mismatch():
+    """If we pass in a string type, we expect it to be converted to bytes"""
+    vddd_list = vDDDLists([time(hour=6, minute=6, second=6)])
+    assert vddd_list.to_ical() == b'060606'