Workarround for this issue : https://github.com/kripken/emscripten/issues/3675

is_directory.cpp

bool fixed_is_directory(std::string path) {
	boost::system::error_code errorCode;
	bool result = boost::filesystem::is_directory(path, errorCode);
	if (errorCode.value() == 2) {//not found 
		return false;
	} else if (errorCode.value() != 0) {
		//this second call will fire the correct exception
		boost::filesystem::is_directory(path);
	} else {
		return result;
	}
}