Getting correct MIME type of a json file containing empty arrays

Question

Using python-magic, I'm trying to guess the mime type of simple files and stumble upon this: if the json contains an empty array, the mime type returned is 'text/plain' instead of 'application/json'.

First, import magic and from pathlib import Path, then correct guess:

>>> content = {'entry': ['data']}
>>> Path('./config.json').write_text(json.dumps(content), encoding='UTF-8')
19
>>> magic.from_file('./config.json', mime=True)
'application/json'
>>>

Incorrect guess:

>>> content = {'entry': []}
>>> Path('./config.json').write_text(json.dumps(content), encoding='UTF-8')
13
>>> magic.from_file('./config.json', mime=True)
'text/plain'
>>>

Why is that so? Is it possible to have a consistent behaviour? Is it a bug in python-magic?

Note: I've explicitely added encoding='UTF-8' but it is useless, it's already the default encoding on my system (as shown by locale.getpreferredencoding(False)).