conll_formatter error -> field_names

[mdhafiz-val]

Hi, I'm currently having an issue when trying to use the spacy_conll

For context, my team and I are in the process of training a pipeline using spaCy, and we have an intermediate pipeline trained on a fraction of our data so far. I've followed all the code provided, but seem to always get this specific error after running the code:
Config error for 'conll_formatter'
conll_formatter -> field_names at root: None is not typing.Dict[str, str]
{'nlp': <spacy.lang.en.English object at 0x000001D7BEEBCBF0>, 'name': 'conll_formatter', 'conversion_maps': None, 'ext_names': None, 'field_names': None, 'include_headers': False, 'disable_pandas': False, '@factories': 'conll_formatter'}

I've tried to work backwards to figure out what went wrong, and while I initially thought it was an issue with my pipeline, I soon realised that I could not even run the sample codes provided. For example, when I tried running one of the sample codes provided in the README.md that could be done on the command line, as listed below:

parse-as-conll en_core_web_sm spacy --input_str "I like cookies. What about you?" --include_headers

It will return the exact same error as above:
Config error for 'conll_formatter'
conll_formatter -> field_names at root: None is not typing.Dict[str, str]
{'nlp': <spacy.lang.en.English object at 0x000001D7BEEBCBF0>, 'name': 'conll_formatter', 'conversion_maps': None, 'ext_names': None, 'field_names': None, 'include_headers': False, 'disable_pandas': False, '@factories': 'conll_formatter'}

Is there something I'm missing in the setting up of the code itself? I hope this query makes sense, and apologise if it's unclear as I'm still rather a novice in comp sci-related issues (am mainly a linguist trying to learn more comp sci for the purposes of computational linguistics)