Cannot reduce an empty iterable w/o an explicit seed value

[Vino]

Hi All,

   Request your help, when i execute the below line of code i am 
getting an error message as "Cannot reduce an empty iterable w/o 
an explicit seed value" , The below lie of code will iterate 
several file system and will report the size of the folder (level 
1) which is greater than 10GB.


Program:
auto coSizeDirList (string FFs, int SizeDir) {
	float subdirTotal;
	float subdirTotalGB;
	Array!string Result;
	auto dFiles = Array!string ((dirEntries(FFs, 
SpanMode.shallow).filter!(a => a.isDir))[].map!(a => a.name));
	foreach (d; parallel(dFiles[], 1)) {
	auto SdFiles = Array!float ((dirEntries(join(["\\\\?\\", d]), 
SpanMode.depth).filter!(a => a.isFile))[].map!(a => 
to!float(a.size)));
	{
	subdirTotalGB = ((reduce!((a,b) => a + b)(SdFiles)) / 1024 / 
1024 / 1024);
				}
  if (subdirTotalGB > SizeDir) {
Result.insertBack(d); Result.insertBack(to!string(subdirTotalGB));
			}
				}
			return Result;
}

From,
Vino.B