deflisten not working with Python scripts

[musjj]

I have no idea what I'm doing wrong here:

#!/usr/bin/env python
import json
import time

while True:
    print(json.dumps({"foo": "bar"}))
    time.sleep(5)

(deflisten foo-bar :initial "{}" "path/to/script")

❯ eww get foo-bar
{}

eww is simply not reading the output of my script. Reading the logs with --debug didn't give me any useful information either.
Can any eww wizards give me the magic incantation that will make this work?

[musjj]

Solved: #514