fix: skip ListElement objects when rendering mixed MetaEntry to avoid crash

When a YAML list mixes dict items (- x: 123) and plain strings (- y),
the parser produces a MetaEntry with both Entry and ListElement children.
ListElement has no to_markdown() method, causing an AttributeError.
Closes #27.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: Chris1221

test/test_examples.py

@@ -237,13 +237,18 @@ def test_simple_no_schema(self):
 
 
 
-class TestComments(unittest.TestCase):
+class TestEdgeCases(unittest.TestCase):
     def test_ordinary_comment_without_colon(self):
         # Regression test for issue #26
         output = get_output("test/yaml/ordinary_comments.yaml")
         self.assertIn("hello world", output)
         self.assertIn("1", output)
 
+    def test_mixed_list_does_not_crash(self):
+        # Regression test for issue #27
+        output = get_output("test/yaml/mixed_list.yaml")
+        self.assertIn("a_list_of_mixed_dict_and_str", output)
+
 
 class TestPackage(unittest.TestCase):
     def test_version_is_set(self):

test/yaml/mixed_list.yaml

@@ -0,0 +1,6 @@
+#' hello world
+a: 1
+
+a_list_of_mixed_dict_and_str:
+  - x: 123
+  - y

yamldoc/entries.py

@@ -82,7 +82,7 @@ def __repr__(self):
 
     def non_excluded_entries(self):
         """Returns a list of entries that are not excluded."""
-        return [entry for entry in self.entries if not entry.exclude]
+        return [entry for entry in self.entries if not entry.exclude and not isinstance(entry, ListElement)]
 
     def table_header(self, schema=False):
         if schema: