❯ bst build hello.bst
Traceback (most recent call last):
  File "/home/fclews/.local/bin/bst", line 8, in <module>
    sys.exit(cli())
  File "/home/fclews/.local/lib/python3.8/site-packages/click/core.py", line 829, in __call__
    return self.main(*args, **kwargs)
  File "/home/fclews/.local/lib/python3.8/site-packages/buildstream/_frontend/cli.py", line 173, in override_main
    original_main(self, args=args, prog_name=prog_name, complete_var=None,
  File "/home/fclews/.local/lib/python3.8/site-packages/click/core.py", line 782, in main
    rv = self.invoke(ctx)
  File "/home/fclews/.local/lib/python3.8/site-packages/click/core.py", line 1259, in invoke
    return _process_result(sub_ctx.command.invoke(sub_ctx))
  File "/home/fclews/.local/lib/python3.8/site-packages/click/core.py", line 1066, in invoke
    return ctx.invoke(self.callback, **ctx.params)
  File "/home/fclews/.local/lib/python3.8/site-packages/click/core.py", line 610, in invoke
    return callback(*args, **kwargs)
  File "/home/fclews/.local/lib/python3.8/site-packages/click/decorators.py", line 33, in new_func
    return f(get_current_context().obj, *args, **kwargs)
  File "/home/fclews/.local/lib/python3.8/site-packages/buildstream/_frontend/cli.py", line 339, in build
    with app.initialized(session_name="Build"):
  File "/usr/lib64/python3.8/contextlib.py", line 113, in __enter__
    return next(self.gen)
  File "/home/fclews/.local/lib/python3.8/site-packages/buildstream/_frontend/app.py", line 178, in initialized
    self.context.load(config)
  File "/home/fclews/.local/lib/python3.8/site-packages/buildstream/_context.py", line 230, in load
    _yaml.node_validate(overrides, ['artifacts', 'options', 'strict', 'default-mirror'])
  File "/home/fclews/.local/lib/python3.8/site-packages/buildstream/_yaml.py", line 952, in node_validate
    invalid = next((key for key in node if key not in valid_keys), None)
TypeError: 'NoneType' object is not iterable