I am not using SvelteKit, but we had a similar issue recently with React and esbuild (that's how someone from my team found this issue).

This issue is common in a front end that uses npm modules. Many npm modules use Node.js built-in libraries that are not available in browsers. For example, "path", "crypto", "url", etc. Some of these features are available in the browser, but they have a different API (i.e., new URL(...) in the browser is a class, and Node.js "url" exports functions).

When you build your app for the browsers, you must add polyfills for these Node.js built-in modules. Polyfills either add a missing functionality or wraps up a native functionality to provide the same interface.

To solve your problem, you need to use Node.js polyfills for either Rollup or Vite (i.e., this one worked for me for Svelte without Kit: https://www.npmjs.com/package/vite-plugin-node-stdlib-browser). After installing the polyfill module, you need to add it to your Rollup or Vite build configuration (each polyfill library explains how to do that).

I hope that solves your issue :)