fix: support for SSR

[paolodamico]

This PR refactors the code posthog-web so the library can be imported in Next.js projects with SSR. Instead of window having to be defined just from importing the library, this relies on window being defined on the constructor (i.e. when an object is initialized).

Before in a Next.JS project

import PostHog from 'posthog-js-lite' // <- this would generate an exception because window is not defined

After (this works)

import PostHog from 'posthog-js-lite';

if (typeof window !== 'undefined') {
    posthog = new PostHog(
        'phc_my_key',
    )
}

CC @m1guelpf

[paolodamico]

In addition, we also get rid of package-lock.json to avoid having two duplicate lock files which can cause confusion or maintenance issues.

[benjackwhite]

This is a great solution, nicely implemented!

Thanks @paolodamico !

[paolodamico]

thx @benjackwhite, appreciate the super quick turnaround! could we trouble you with pushing a release so we can ship our app?

[paularmstrong]

This still needs to be gated because it is still throwing a ReferenceError – you can't just reference window in the node.js global scope.

this._storage = getStorage(options?.persistence || 'localStorage', typeof window !== 'undefined' ? window : undefined)