"o.featureFlags.overrideFeatureFlags is not a function" when using feature toggle from toolbar

[psalv]

Bug Description

Bug description

Overriding features flags appears to have an error (launching in fresh incognito from the "Launch toolbar" tool in the Posthog app).

Uncaught TypeError: o.featureFlags.overrideFeatureFlags is not a function
    at setOverriddenUserFlag (flagsToolbarLogic.ts:178:44)
    at index.cjs.js:1245:24
    at Object.dispatch (index.cjs.js:1980:19)
    at t.actions.<computed> (index.cjs.js:1367:28)
    at onChange (FlagsToolbarMenu.tsx:95:53)
    at onClick (LemonSwitch.tsx:77:25)

posthog-js version: ^1.215.5 (latest)

My app is being built with vite version ^5.4.1

I'm a bit stumped what could be going wrong here but it feels like this commit is related PostHog/posthog-js@690773b

posthog/frontend/src/toolbar/flags/flagsToolbarLogic.ts

Line 178 in 0e0b968

clientPostHog.featureFlags.overrideFeatureFlags({

Debug info

Session: https://us.posthog.com/project/sTMFPsFhdP1Ssg/replay/0194dd72-08bc-77a6-b721-81244f860de4?t=2420
Admin: http://go/adminOrgUS/01945cc7-3c26-0000-b2fe-808c574fd25f (project ID 117481)
Sentry: http://go/sentryUS/117481

[pefernandez]

Having the same issue.

Uncaught TypeError: o.featureFlags.overrideFeatureFlags is not a function
    at setOverriddenUserFlag (toolbar.js?t=1738921500000:36:73173)
    at toolbar.js?t=1738921500000:10:10493
    at Object.dispatch (toolbar.js?t=1738921500000:10:22661)
    at t.actions.<computed> (toolbar.js?t=1738921500000:10:12293)
    at onChange (toolbar.js?t=1738921500000:36:75316)
    at onClick (toolbar.js?t=1738921500000:26:113521)
    at Object.Cw (toolbar.js?t=1738921500000:6:9867)
    at Sw (toolbar.js?t=1738921500000:6:10021)
    at yw (toolbar.js?t=1738921500000:6:10078)
    at Ax (toolbar.js?t=1738921500000:6:31460)

Any browser.