In local development StatsD is raising `OSError: [WinError 10049] The requested address is not valid in its context` when env variable `STATSD_HOST` is not set. This seems to just be a Windows issue as the error suggests, because I can't get it to happen inside Docker.

This is happening because the default empty string of `settings.STATSD_HOST` gets set as the default host of `statsd.Connection`, and the empty string is not a valid host name in Windows.

https://github.com/PostHog/posthog/blob/1357df0c137e36478be19a1b8739dcdba93d2327/posthog/settings.py#L181
https://github.com/PostHog/posthog/blob/1ec12f26e707489e77077be029ddb79ceeefd944/posthog/celery.py#L35

StatsD sets the default `host` value to `'localhost'`, and restoring this default fixes the errors. I can make a PR tomorrow, but just wanted to check on this:
https://github.com/PostHog/posthog/blob/1357df0c137e36478be19a1b8739dcdba93d2327/posthog/settings.py#L217-L219

I can change it to `if os.environ.get("STATSD_HOST", False):`, but it might make more sense as a separate env variable like `STATSD_ENABLED`. My only concern with that is it's probably a breaking change. Are there any better options?



posthog/settings.py
# Use django-extensions if it exists
try:
    import django_extensions  # noqa: F401
except ImportError:
    pass
else:
    INSTALLED_APPS.append("django_extensions")
INTERNAL_IPS = ["127.0.0.1", "172.18.0.1"]  # Docker IP
CORS_ORIGIN_ALLOW_ALL = True
# Max size of a POST body (for event ingestion)
DATA_UPLOAD_MAX_MEMORY_SIZE = 20971520  # 20 MB
ROOT_URLCONF = "posthog.urls"
TEMPLATES = [
    {
        "BACKEND": "django.template.backends.django.DjangoTemplates",
        "DIRS": ["frontend/dist", "posthog/templates"],
        "APP_DIRS": True,
        "OPTIONS": {
            "context_processors": [
                "django.template.context_processors.debug",
                "django.template.context_processors.request",
                "django.contrib.auth.context_processors.auth",
                "django.contrib.messages.context_processors.messages",
            ],
        },
    },
]
WSGI_APPLICATION = "posthog.wsgi.application"
# Social Auth
SOCIAL_AUTH_POSTGRES_JSONFIELD = True