Allow zero items to be passed to add_options and do zero work

src/textual/widgets/_option_list.py

@@ -520,6 +520,9 @@ class OptionList(ScrollView, can_focus=True):
         Raises:
             DuplicateID: If there is an attempt to use a duplicate ID.
         """
+        # Only work if we have items to add; but don't make a fuss out of
+        # zero items to add, just carry on like nothing happened.
+        if items:
             # Turn any incoming values into valid content for the list.
             content = [self._make_content(item) for item in items]
             self._contents.extend(content)

tests/option_list/test_option_list_create.py

@@ -110,6 +110,10 @@ async def test_add_later() -> None:
             [Option("more still"), "Yet more options", "so many options!"]
         )
         assert option_list.option_count == 10
+        option_list.add_option(None)
+        assert option_list.option_count == 10
+        option_list.add_options([])
+        assert option_list.option_count == 10
 
 
 async def test_create_with_duplicate_id() -> None: