Worker setup causing variable not defined

[Justineo]

Describe the bug

I am importing and instantiating a worker in WXT, but the added iifeReturnValueName leads to accessing an undefined variable.

Reproduction

https://github.com/Justineo/wxt-repro

Steps to reproduce

1. Clone the repo.
2. Run pnpm dev.
3. Side-load the extension in Chrome.
4. Open the console and navigate to any webpage.

And in the console you will see:

Uncaught ReferenceError: content is not defined

worker.ts is transformed into:

(function() {
  "use strict";
  console.log("From worker");
  content;
})();
content;

Where content is not defined.

System Info

System:
    OS: macOS 14.6.1
    CPU: (14) arm64 Apple M3 Max
    Memory: 52.42 MB / 36.00 GB
    Shell: 5.9 - /bin/zsh
  Binaries:
    Node: 22.13.0 - ~/.volta/tools/image/node/22.13.0/bin/node
    npm: 10.9.2 - ~/.volta/tools/image/node/22.13.0/bin/npm
    pnpm: 9.15.5 - ~/.volta/bin/pnpm
  Browsers:
    Chrome: 133.0.6943.54
    Chrome Canary: 135.0.7012.0
    Edge: 133.0.3065.59
    Safari: 18.0
  npmPackages:
    wxt: ^0.19.13 => 0.19.27

Used Package Manager

pnpm

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