How would I go about adding a compiler option to emscripten for building to html5?

so I’m now running the unreal engine I got off github and have added --bind to the getlinkarguments function, but now when I build for html5 it gets stuck at:

UATHelper: Packaging (HTML5): UnrealBuildTool: #include “…” search starts here:
UATHelper: Packaging (HTML5): UnrealBuildTool: #include <…> search starts here:
A list of paths in the engine folders where include header files may exist
UATHelper: Packaging (HTML5): UnrealBuildTool: End of search list.

I can see in the output log right above this output that the --bind did something because now it has bind.cpp as the last thing when it tries to Link myproject.js.

I’m guessing one of the header files in bind.cpp can’t be found at the locations listed? I’ve also found some posts where the original unresolved symbol errors in emscripten I was seeing are actually just warnings? Can I disable show warnings as errors on my custom ue4?