// subPath is relative and with slashes
static InputStream inputStreamForFileInDirOrZip(File location, S subPath) ctex {
  if (location.isDirectory()) {
    File f = new File(location, subPath);
    ret f.exists() ? newFileInputStream(f) : null;
  } else if (location.isFile()) {
    InputStream in = zipFileInputStream(location, subPath);
    if (in != null) ret in;
  }
  null;
}

Began life as a copy of #1012231