browser.i18n.getMessage does not work on Safari extension:

Describe the bug

I am building an extension MV3 supports multiple languages with WXT ^0.19.26,
it works well on Edge Chrome, but not Safari.

Reproduction

Archive.zip

Steps to reproduce

1. create a wxt-demo

2. add a demo options page calling browser.i18n.getMessage

const _ = browser.i18n.getMessage;
...
<h1>{_("Options")}</h1>

create message files public/_locales/{en,zh_TW}/messages.json

3. build chrome extension pnpm i && pnpm build

4. generate safari extension

xcrun safari-web-extension-converter \
--project-location . \
--app-name WXTDemo \
--bundle-identifier info.wxt.demo \
--objc \
--macos-only \
--no-prompt \
--no-open \
--force \
.output/chrome-mv3

5. build safari extension with Xcode

6. Launch Safari and load the un-sign extension WXTDemo

open Options page,
WANT <h1>{_("Options")}</h1> => <h1>Options</h1> ,
GOT <h1></h1> .

System Info

System:
    OS: macOS 14
  Binaries:
    Node: 23.3.0 - /opt/homebrew/bin/node
    npm: 10.9.0 - /opt/homebrew/bin/npm
    pnpm: 9.15.3 - ~/Library/pnpm/pnpm
    bun: 1.1.34 - /opt/homebrew/bin/bun
    Watchman: 2024.12.02.00 - /opt/homebrew/bin/watchman
  Browsers:
    Chrome: 132.0.6834.160
    Edge: 132.0.2957.127
    Safari: 17.4
  npmPackages:
    wxt: ^0.19.26 => 0.19.26

Used Package Manager

pnpm

Validations

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• The provided reproduction is a minimal reproducible example of the bug.

Start with the attached Archive.zip and the options page that calls browser.i18n.getMessage, then inspect public/_locales/{en,zh_TW}/messages.json and the generated .output/chrome-mv3 extension. Reproduce the Safari conversion and build steps; done means the Safari options page renders “Options” instead of an empty heading.