reproduction for vitejs/vite#9197

git clone git@github.com:Rich-Harris/vite-ssrloadmodule-strict-repro.git
cd vite-ssrloadmodule-strict-repro
pnpm install # or npm install
npm test

Expected

test:dev should fail, because we're assigning to an undeclared variable, which is forbidden in strict mode (which applies to all modules implicitly). We should never get as far as the >>> TESTING BUILD stage.

Actual

test:dev completes, because the code is not being run in strict mode.