Asynchronous calls of ´isFeatureEnabled´ fail to resolve

[babasbot]

Bug description

Asynchronous calls of isFeatureEnabled fail to resolve when no personal API key is provided.

Tested on:

• posthog-node@2.4.0.
• Node v16.8.0

How to reproduce

import { PostHog } from "posthog-node";

const { POSTHOG_API_KEY } = process.env;

if (!POSTHOG_API_KEY) {
    throw Error("PostHog API key not provided.");
}

const posthog = new PostHog(POSTHOG_API_KEY);

async function main() {
    const distinctId = "1337";
    const key = "AWESOME_FEATURE";

    const featureFlags = await Promise.all([
        posthog.isFeatureEnabled(key, distinctId),
        posthog.isFeatureEnabled(key, distinctId),
        posthog.isFeatureEnabled(key, distinctId),
        posthog.isFeatureEnabled(key, distinctId),
        posthog.isFeatureEnabled(key, distinctId),
        posthog.isFeatureEnabled(key, distinctId),
        posthog.isFeatureEnabled(key, distinctId),
        posthog.isFeatureEnabled(key, distinctId),
    ]);

    console.log(featureFlags);
}

main()
    .then(() => {
        process.exit(0);
    })
    .catch((err) => {
        console.error(err);
        process.exit(-1);
    });

The expected result would be:

[
  true, true,
  true, true,
  true, true,
  true, true
]

But instead, we got:

[
  undefined, true,
  undefined, undefined,
  undefined, undefined,
  undefined, undefined
]

Related sub-libraries

• [ ] All of them
• [ ] posthog-web
• [x] posthog-node
• [ ] posthog-react-native

Additional context

• If we provide a personal API key, the feature flags will be evaluated as expected.
• If we individually await the isFeatureEnabled calls instead of grouping them inside a Promise.all, the feature flags will be evaluated correctly.

for (let i = 0; i < 8; i++) {
    const ff = await posthog.isFeatureEnabled(key, distinctId);
    console.log(ff);
}
// -> false
// -> false
// -> false
// -> false
// -> false
// -> false
// -> false
// -> false

[neilkakkar]

Hey @babasbot , mind checking if this holds true on v2.5.0 as well please? It was released today, with a pretty big change to how the internals here work.

Thanks!

[babasbot]

It is working as expected on 2.5.0; thank you! 🖖