Fix a parse issue and get 100% test coverage

Author: davepeck

html_tstring/parser.py

@@ -44,6 +44,8 @@ def handle_endtag(self, tag: str) -> None:
             if most_recent_closed and most_recent_closed.tag == tag:
                 # Ignore this call; we've already closed it.
                 return
+
+        if not self.stack:
             raise ValueError(f"Unexpected closing tag </{tag}> with no open element.")
 
         element = self.stack.pop()

html_tstring/parser_test.py

@@ -165,6 +165,11 @@ def test_parse_unclosed_tag():
         _ = parse_html("<div>Unclosed")
 
 
+def test_parse_unexpected_closing_tag():
+    with pytest.raises(ValueError):
+        _ = parse_html("Unopened</div>")
+
+
 def test_parse_html_iter_preserves_chunks():
     chunks = [
         "<div>",