General

This repo deals with an issue which results in a combination of using pnpm as package manager, vite with specific vite.config.ts (preserveSymlinks:true) and a svelte kit application which uses "redirect" function in a sever component.

The redirect function is implemted as follows, it will throw a Redirect Class

export function redirect(status, location) {
	if ((!BROWSER || DEV) && (isNaN(status) || status < 300 || status > 308)) {
		throw new Error('Invalid status code');
	}

	throw new Redirect(
		// @ts-ignore
		status,
		location.toString()
	);
}

Within the svelte kit framework a module checks whether the caught error is a Redirect or not.

The svelte kit application uses a default javascript api "instanceof" to check whether an thrown error is a Redirect Class or not. If a redirect is detected the application redirects the user.

If the check fails the user will not be redirected. The implementation can be found in "@sveltejs/kit/src/runtime/server/page/index.js within method render_page line 208"

if (err instanceof Redirect) {
    if (state.prerendering && should_prerender_data) {
        const body = JSON.stringify({
            type: 'redirect',
            location: err.location
        });

        state.prerendering.dependencies.set(data_pathname, {
            response: text(body),
            body
        });
    }

    return redirect_response(err.status, err.location);
}

There is a direct influence of this behavour in regard to the vite.config.ts setting preserveSymlinks.

If "preserveSymlinks" is set to true the instanceof check will fail and the user is not redirected at all.

If "preserveSymlinks" is set to false the user is redirected.

To Reproduce

• install pnpm globally
• install all dependencies by pnpm install
• run dev mode 'pnpm run dev'

Be aware

• currently the instanceof check will fail because preserveSymlinks is set to true, the user is not redirected and a 500 Error Page is shown
• the instanceof check will succeed if the preserveSymlinks is set to false and the user will be redirected correctly