Emscripten uses dynamic `import(fullUrlOfTheMainJS)` in generated Workers.
It appears that upstream rollup-plugin-off-main-thread never handled this correctly, but we had a customization in Squoosh loader template that allowed those anyway, which I removed together with most other customizations in #1007, thus breaking Emscripten codecs.
This adds a hotfix back, but we need to fix this properly upstream too (TBD separately).