[bug] conan graph build-order --order=configuration raising with stacktrace

[AbrilRBS]

Environment details

• Operating System+version: Latest macos
• Conan version: 2.1.0-dev
• Python version: 3.11

Steps to reproduce

Running conan graph build-order --requires=ffmpeg/6.1 --order=configuration currently raises with an stack trace. I'm investigating with @jcar87

Logs

======== Computing the build order ========
ERROR: Traceback (most recent call last):
  File "/Users/ruben/coding/build-tools/venv/lib/python3.11/site-packages/conan/cli/cli.py", line 281, in main
    cli.run(args)
  File "/Users/ruben/coding/build-tools/venv/lib/python3.11/site-packages/conan/cli/cli.py", line 191, in run
    command.run(self._conan_api, args[0][1:])
  File "/Users/ruben/coding/build-tools/venv/lib/python3.11/site-packages/conan/cli/command.py", line 158, in run
    sub.run(conan_api, parser, *args)
  File "/Users/ruben/coding/build-tools/venv/lib/python3.11/site-packages/conan/cli/command.py", line 174, in run
    self._format(parent_parser, info, *args)
  File "/Users/ruben/coding/build-tools/venv/lib/python3.11/site-packages/conan/cli/command.py", line 98, in _format
    formatter(info)
  File "/Users/ruben/coding/build-tools/venv/lib/python3.11/site-packages/conan/cli/commands/graph.py", line 44, in cli_build_order
    for package_level in item['packages']:
                         ~~~~^^^^^^^^^^^^
KeyError: 'packages'

ERROR: 'packages'