chaos report crashes when using a ref in method

[zeisss]

$ docker run     --user $(id -u)     -v $(pwd):/tmp/result     -it     chaostoolkit/reporting report journal.json  out.txt
Traceback (most recent call last):
  File "/usr/local/bin/chaos", line 11, in <module>
    sys.exit(cli())
  File "/usr/local/lib/python3.6/site-packages/click/core.py", line 764, in __call__
    return self.main(*args, **kwargs)
  File "/usr/local/lib/python3.6/site-packages/click/core.py", line 717, in main
    rv = self.invoke(ctx)
  File "/usr/local/lib/python3.6/site-packages/click/core.py", line 1137, in invoke
    return _process_result(sub_ctx.command.invoke(sub_ctx))
  File "/usr/local/lib/python3.6/site-packages/click/core.py", line 956, in invoke
    return ctx.invoke(self.callback, **ctx.params)
  File "/usr/local/lib/python3.6/site-packages/click/core.py", line 555, in invoke
    return callback(*args, **kwargs)
  File "/usr/local/lib/python3.6/site-packages/chaosreport/cli.py", line 31, in report
    reports.append(generate_report(journal, export_format))
  File "/usr/local/lib/python3.6/site-packages/chaosreport/__init__.py", line 227, in generate_report
    filter(lambda a: a["type"] == "probe", experiment["method"])))
  File "/usr/local/lib/python3.6/site-packages/chaosreport/__init__.py", line 227, in <lambda>
    filter(lambda a: a["type"] == "probe", experiment["method"])))
KeyError: 'type'

Looking at experiment["method"] in my journal.json I notice that there is one element having no type:

<snip>
    "method": [
      {
        "ref": "get consul proxy state"
      },
<snip>

Removing the ref probe fixes the crash.