POST http://localhost:8080/stdio.html 405 (Method Not Allowed)

**Version of emscripten/emsdk:**
emcc (Emscripten gcc/clang-like replacement + linker emulating GNU ld) 3.1.42-git
clang version 17.0.0 (https://github.com/llvm/llvm-project.git f3b64887de61020c09404bfee97b2fadd30df10a)
Target: wasm32-unknown-emscripten
Thread model: posix

I have passed in "USE_PTHREADS=1" and "-pthread" compiler flags.
But still looks like ENVIRONMENT_IS_PTHREAD is undefined. (see code below)
I don't find stdio.html anywhere in the directory structure.

`if (typeof window == "object" && (typeof ENVIRONMENT_IS_PTHREAD == "undefined" || !ENVIRONMENT_IS_PTHREAD)) {
blah blah
http.open("POST", "stdio.html", false);
blah blah
`

What can I do about this error?