SyntaxError: Unexpected token '<'

[sentry]

Sentry Issue: NEXU-DESKTOP-PROD-17

SyntaxError: Unexpected token '<'
  at None (/array/phc_rQVGnXNbrmzFMuQfMabpAMAQA8cgU3EbivZWTqDzThtz/config.js:1:1)

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[lefarcen]

Quick triage from the stack:

The throw site is posthog.init(...) in apps/desktop/src/main.tsx:181. posthog-js fetches its per-project remote config from ${api_host}/array/{key}/config.js and evaluates it as JavaScript. Unexpected token '<' at 1:1 means the response body started with < — HTML, not JS — for that request.

Most likely causes, in order:

• An intermediary between the user and us.i.posthog.com (corporate proxy, captive portal, ISP filter, ad-blocker network rule) returning an HTML error / sign-in page instead of passing the request through.
• A self-hosted POSTHOG_HOST override (VITE_POSTHOG_HOST / runtimeConfig.posthogHost) pointing at a host that doesn't serve /array/{key}/config.js correctly — typically a reverse-proxy path-rewrite gap.
• Transient PostHog edge 5xx returning an HTML error page.

It reaches Sentry because the renderer's global window.addEventListener("error", ...) handler (main.tsx:108) forwards the SyntaxError, so each affected session produces one event.

Suggested next steps:

1. Open the Sentry issue and look at event count + user-agent / region distribution. If it's a small tail of scattered users, this is environment-side noise and the cleanest fix is a Sentry inbound filter on SyntaxError: Unexpected token '<' scoped to URL paths matching /array/phc_*/config.js.
2. If a single fingerprint is repeating, capture the affected user's posthogHost via the diagnostics export and verify the override actually serves JS from /array/{key}/config.js.
3. Optional hardening: wrap initializePostHogTelemetry() so PostHog bootstrap failures are tagged separately (e.g. tags: { component: "posthog-bootstrap" }) and don't surface as generic renderer SyntaxErrors.

Adding area/frontend since this is desktop renderer. Not adding help wanted — the right call here (Sentry filter vs. code hardening vs. proxy fix) is a team judgment, not a community-contribution shape.