Find what causes `dev` to behave different from `build+preview`

[lukaw3d]

          > > This is annoying for developing

I can change the web server to process.env.CI ? <preview> : <dev>?

Meh, maybe. We should really find what causes dev to behave different from build+preview

Originally posted by @lukaw3d in #255 (comment)

Make a reproducible example to report upstream

[lukaw3d]

It happens even if I disable minification

export default defineConfig({
  plugins: [nodePolyfills(), svgr(), react()],
  base: '/',
  build: {
    sourcemap: true,
+    minify: false,
+    rollupOptions: {
+      preserveEntrySignatures: true,
+      output: {
+        preserveModules: true,
+      }
+    }
  },