preprocess requires files to exist even @if they will not be included

[dtsamitros]

I have the following optional include

// @if PROJ_BUILD='dynamic'
// @include dynamic_script.js
// @endif

even if PROJ_BUILD is not 'dynamic' still the file is still required to exist in the filesystem although it will not be included and an error is raised

node_modules\preprocess\lib\preprocess.js:380
      throw new Error(errMsg);
            ^
Error: dynamic_script.js requested from main.min.js not found!

I know there is the fileNotFoundSilentFail option but it does not feel right to use in this case

Thank you, Dimitris