fix: optional-chain import.meta.env to prevent SSR crash when externalized

[yogeshchoudhary147]

Problem

Auth0Provider crashes on first render when the package is installed from npm and Vite externalizes it. The CJS build (via tsup) replaces import.meta with {}, so import.meta.env is undefined. Accessing undefined.VITE_AUTH0_DOMAIN throws a TypeError.

The same crash occurs in Node.js ESM SSR since import.meta.env is a Vite construct — not available in plain Node.js.

Workaround in the sample app: ssr: { noExternal: ["@auth0/auth0-react-router"] } in vite.config.ts.

Fix

Add ?. optional chaining to all import.meta.env accesses (11 sites) in Auth0Provider.tsx. When env is undefined, every access safely returns undefined instead of throwing — isSpa evaluates to false and the SSR provider renders normally.

Test

Added a regression test in ssr-provider.test.tsx that sets import.meta.env = undefined at runtime (simulating the externalized CJS scenario) and asserts Auth0Provider does not throw.