sveltekit220

A minimal reproduction of an issue introduced in sveltekit 2.20 https://github.com/sveltejs/kit/issues/13630

Instructions to Reproduce the Issue

The following has already been configured in current repo:

1. Dependencies

   • Ensure @sveltejs/kit is at a version later than 2.19.2. It can be 2.20.0, 2.20.1 or 2.20.2.

   • Ensure vite-plugin-top-level-await is a dependency and is correctly setup in vite.config.ts.

2. Hooks

   • You must have a hooks.server.ts file. A minimal configuration is enough for reproduction.

3. Emulate a Production Environment

   Run the following command. It will compile the sveltekit app and run a minimum production server.

   make prod
   

4. Expected Error

   The production server will end up with the following error:

   file:///build/handler.js:1174
   const server = new Server(manifest);
               ^
   TypeError: Server is not a constructor
       at file:///build/handler.js:1174:16
       at ModuleJob.run (node:internal/modules/esm/module_job:271:25)
       at async onImport.tracePromise.__proto__ (node:internal/modules/esm/loader:578:26)
       at async asyncRunEntryPointWithESMLoader (node:internal/modules/run_main:116:5)
   

Experiments

No Issue in Development Environment

The following command produced a development server. It has no issues.

make dev

No Issue with SvelteKit 2.19.2

Only modify @sveltejs/kit in app/package.json from 2.20.2 to 2.19.2. Keep everything else unmodified. Rerun make prod. No issue.

No Issue After Removing vite-plugin-top-level-await

Only remove vite-plugin-top-level-await from app/package.json and app/vite.config.ts. Keep everything else unmodified. Rerun make prod. No issue.

No Issue After Deleting hooks.server.ts

Only delete file app/src/hooks.server.ts. Keep everything else unmodified. Rerun make prod. No issue.

Conclusion

When vite-plugin-top-level-await is used and hooks.server.ts exists, SvelteKit 2.20.0 introduced an issue to NodeJS runtime.

Workaround

1. If vite-plugin-top-level-await and hooks.server.ts are absolutely required, use SvelteKit 2.19.2 instead.
2. If only need to support new browsers, vite-plugin-top-level-await can then be avoided by setting build.target as esnext in vite.config.ts.