Don't delete ErrorNode names. They are part of the parser now.

Fixes #594 and possibly also #590 and #579.

test/test_parser/test_parser.py

@@ -213,3 +213,8 @@ def test_backslash_dos_style():
     grammar = load_grammar()
     m = ParserWithRecovery(grammar, u('\\\r\n')).module
     assert m
+
+
+def test_started_lambda_stmt():
+    p = ParserWithRecovery(load_grammar(), 'lambda a, b: a i')
+    assert p.get_parsed_node().children[0].type == 'error_node'