`onMount` No Longer Being Invoked on Svelte Upgrade v3.59.1 -> 4.0.5

[stricklandrbls]

Describe the bug

In my VSCode extension, I am using Svelte for the UI of my web panel. I have created multiple .svelte components that have onMount running fine in Svelte v3.59.1 and Svelte-Check v3.4.3.

I recently upgrade Svelte to 4.0.5 and Svelte-Check to 3.4.5 and ever since this upgrade, none of the onMount functions in any of my components are being invoked.

Reproduction

Link to GitHub Repo Files
https://github.com/ctc-oss/daffodil-vscode/blob/implement-highlevel-svelte-components/src/svelte/src/components/DataDisplays/CustomByteDisplay/DataLineFeed.svelte

https://github.com/ctc-oss/daffodil-vscode/blob/implement-highlevel-svelte-components/src/svelte/src/components/DataDisplays/DataViewports.svelte

https://github.com/ctc-oss/daffodil-vscode/blob/implement-highlevel-svelte-components/src/svelte/src/components/Header/fieldsets/SearchReplace.svelte

Logs

No response

System Info

System:
    OS: Linux 6.2 Pop!_OS 22.04 LTS
    CPU: (12) x64 Intel(R) Core(TM) i7-8700K CPU @ 3.70GHz
    Memory: 20.95 GB / 31.26 GB
    Container: Yes
    Shell: 5.1.16 - /bin/bash
  Binaries:
    Node: 18.16.0 - ~/.local/bin/node
    Yarn: 1.22.19 - ~/.local/bin/yarn
    npm: 9.5.1 - ~/.local/bin/npm
    pnpm: 8.6.7 - ~/.local/bin/pnpm

### Severity

blocking an upgrade

[gtm-nayan]

Duplicate of #8953

[gtm-nayan]

Add browser: true to your plugin-node-resolve, #8953 (comment)

[scholarsmate]

Thanks for this fix. I too was bitten by this change. Adding browser: true to the resolve section in my rollup.config.js worked. I didn't see anything about having to do this in the migration from v3 to v4 guide, but I think it deserves a mention as I'm sure many of us who are migrating will have this same problem.

    resolve({
      exportConditions: ['svelte'],
      extensions: ['.svelte'],
      dedupe: ['svelte'],
      browser: true,
    }),