#480 Dump restor issue on empty document

[Stéphane Brunner @ camptocampSA]

The following code:

from ruamel.yaml import YAML
import io
import sys

yaml=YAML()

io = io.StringIO("# hi\n{}")
data = yaml.load(io)
yaml.dump(data, sys.stdout)

Raise the exception:

Traceback (most recent call last):
  File "/home/sbrunner/workspace/deskew/test.py", line 9, in <module>
    yaml.dump(data, sys.stdout)
  File "/home/sbrunner/.local/lib/python3.10/site-packages/ruamel/yaml/main.py", line 567, in dump
    return self.dump_all([data], stream, transform=transform)
  File "/home/sbrunner/.local/lib/python3.10/site-packages/ruamel/yaml/main.py", line 577, in dump_all
    self._context_manager.dump(data)
  File "/home/sbrunner/.local/lib/python3.10/site-packages/ruamel/yaml/main.py", line 913, in dump
    self._yaml.representer.represent(data)
  File "/home/sbrunner/.local/lib/python3.10/site-packages/ruamel/yaml/representer.py", line 82, in represent
    self.serializer.serialize(node)
  File "/home/sbrunner/.local/lib/python3.10/site-packages/ruamel/yaml/serializer.py", line 109, in serialize
    self.serialize_node(node, None, None)
  File "/home/sbrunner/.local/lib/python3.10/site-packages/ruamel/yaml/serializer.py", line 226, in serialize_node
    self.emitter.emit(MappingEndEvent(comment=[map_comment, end_comment]))
  File "/home/sbrunner/.local/lib/python3.10/site-packages/ruamel/yaml/emitter.py", line 254, in emit
    self.state()
  File "/home/sbrunner/.local/lib/python3.10/site-packages/ruamel/yaml/emitter.py", line 383, in expect_document_root
    self.expect_node(root=True)
  File "/home/sbrunner/.local/lib/python3.10/site-packages/ruamel/yaml/emitter.py", line 451, in expect_node
    force_flow_indent = not self.indents.values[-1][1]
IndexError: list index out of range

[Anthon van der Neut]

This should be fixed in 0.17.36, Thanks for reporting.