WebAssembly app doesn't start in the browser with the --proxy-to-worker compilation flag

It looks like Qt is creating non-working HTML and JS code to run the wasm-program "Hello World!" with the "--proxy-to-worker" flag. Because the same application without qt and with this flag works fine. I tried running in different browsers on different OS, but the result is the same.

Еrror in the browser:

"TypeError: Cannot read property 'addEventListener' of undefined"

The exception is always on the same line.