add options ignoreNoMatch to ignore zero check (#121)

Author: tarol

lib/actions/copy.js

@@ -45,7 +45,7 @@ exports.copy = function (from, to, options, context, tplSettings) {
   }
 
   // Sanity checks: Makes sure we copy at least one file.
-  assert(files.length > 0, 'Trying to copy from a source that does not exist: ' + from);
+  assert(options.ignoreNoMatch || files.length > 0, 'Trying to copy from a source that does not exist: ' + from);
 
   files.forEach(file => {
     this._copySingle(file, generateDestination(file), options, context, tplSettings);