master currently fails on running examples

https://gitlab.aicrowd.com/flatland/flatland/-/jobs/4895

  File "benchmarks/profile_all_examples.py", line 34, in <module>
    profile('examples', entry)
  File "benchmarks/profile_all_examples.py", line 24, in profile
    cProfile.run('my_func()', sort='time')
  File "/builds/flatland/flatland/.tox/profiling/lib/python3.6/cProfile.py", line 16, in run
    return _pyprofile._Utils(Profile).run(statement, filename, sort)
  File "/builds/flatland/flatland/.tox/profiling/lib/python3.6/profile.py", line 55, in run
    prof.run(statement)
  File "/builds/flatland/flatland/.tox/profiling/lib/python3.6/cProfile.py", line 95, in run
    return self.runctx(cmd, dict, dict)
  File "/builds/flatland/flatland/.tox/profiling/lib/python3.6/cProfile.py", line 100, in runctx
    exec(cmd, globals, locals)
  File "<string>", line 1, in <module>
  File "benchmarks/profile_all_examples.py", line 22, in my_func
    def my_func(): runpy.run_path(file_in, run_name="__main__")
  File "/builds/flatland/flatland/.tox/profiling/lib/python3.6/runpy.py", line 263, in run_path
    pkg_name=pkg_name, script_name=fname)
  File "/builds/flatland/flatland/.tox/profiling/lib/python3.6/runpy.py", line 96, in _run_module_code
    mod_name, mod_spec, pkg_name, script_name)
  File "/builds/flatland/flatland/.tox/profiling/lib/python3.6/runpy.py", line 85, in _run_code
    exec(code, run_globals)
  File "/builds/flatland/flatland/examples/custom_observation_example_02_SingleAgentNavigationObs.py", line 102, in <module>
    main(sys.argv[1:])
  File "/builds/flatland/flatland/examples/custom_observation_example_02_SingleAgentNavigationObs.py", line 83, in main
    obs, info = env.reset()
  File "/builds/flatland/flatland/flatland/envs/rail_env.py", line 384, in reset
    observation_dict: Dict = self._get_observations()
  File "/builds/flatland/flatland/flatland/envs/rail_env.py", line 720, in _get_observations
    self.obs_dict = self.obs_builder.get_many(list(range(self.get_num_agents())))
  File "/builds/flatland/flatland/flatland/core/env_observation_builder.py", line 55, in get_many
    observations[h] = self.get(h)
  File "/builds/flatland/flatland/examples/custom_observation_example_02_SingleAgentNavigationObs.py", line 38, in get
    possible_transitions = self.env.rail.get_transitions(*agent.position, agent.direction)
TypeError: get_transitions() argument after * must be an iterable, not NoneType
ERROR: InvocationError for command /builds/flatland/flatland/.tox/profiling/bin/python benchmarks/profile_all_examples.py (exited with code 1)
___________________________________ summary ____________________________________
ERROR:   benchmarks: commands failed
ERROR:   profiling: commands failed
ERROR: Job failed: command terminated with exit code 1