benedict.to_json returns empty dict for benedict from generator

[kranonetka]

Python version
Python 3.8.3

Package version
python-benedict==0.21.0

Current behavior (bug description)
bededict.to_json for benedict from generator returns '{}' instead of json dumped dict

Expected behavior
bededict.to_json should return actual json dumped dict

Steps to reproduce

from benedict import benedict


def gen_dict():
    for k, v in enumerate('abcd'):
        yield k, v


if __name__ == '__main__':
    b = benedict(gen_dict())
    assert b == {0: 'a', 1: 'b', 2: 'c', 3: 'd'}
    assert b.to_json()  ==  '{"0": "a", "1": "b", "2": "c", "3": "d"}'

But if recast benedict to dict and back to benedict it works fine

if __name__ == '__main__':
    b = benedict(gen_dict())
    b = benedict(dict(b))
    assert b == {0: 'a', 1: 'b', 2: 'c', 3: 'd'}
    assert b.to_json()  ==  '{"0": "a", "1": "b", "2": "c", "3": "d"}'

[fabiocaccamo]

You can upgrade to 0.21.1 version.