Subscriptions "Complete Example" breaks under 0.10.0

I’m working with Subscriptions in ariadne using the exact code from the Complete Example in the docs. When I load the playground and issue the query subscription { counter }, instead of a working counter, an “unsupported operand” error is raised:

Traceback (most recent call last):",
  File \"/Users/...REDACTED.../virtualenvs/graphql-Pfr5HTvn/lib/python3.7/site-packages/graphql/execution/execute.py\", line 625, in resolve_field_value_or_error",
    result = resolve_fn(source, info, **args)",
  File \"/Users/...REDACTED.../app/__init__.py\", line 26, in counter_resolver",
    return count + 1",
TypeError: unsupported operand type(s) for +: 'NoneType' and 'int'"

What’s wild is that the example in the docs works with ariadne 0.8.0 and 0.9.0, but not 0.10.0. I’m not familiar enough with the internals, though, to spot the issue in the 0.9.0…0.10.0 diff.

(For completeness, I’m using Python 3.7.6, ariadne 0.10.0, under uvicorn 0.11.2 and gunicorn 20.0.4.)

[shaozi]

my bad. I am using uvicorn, turns out I also need to pip install websockets for the server to support web sockets

[rafalp]

We’ve just merged the fix for this. I’m expecting we’ll release Ariadne 0.11 with it in few days.