fix cb non called if no task_path

Author: Amoki

README.md

@@ -42,7 +42,7 @@ And then:
 var anyfetchHydrater = require('anyfetch-hydrater');
 
 var config = {
-  'hydrater_function': 'path/to/my/function.js'
+  'hydrater_function': 'absolute/path/to/my/function.js'
 };
 
 var hydrationServer = anyfetchHydrater.createServer(config);

lib/helpers/child-process.js

@@ -7,7 +7,7 @@
  * the master process can simply kill the child and resume its normal operation.
  * Without the sub-process isolation, we get stuck quite fast and get leaks everywhere.
  */
- 
+
 var crypto = require('crypto');
 var async = require("async");
 var fs = require('fs');
@@ -60,6 +60,9 @@ process.on('message', function(task) {
       if(task.file_path) {
         fs.unlink(path, rarity.carry([changes], cb));
       }
+      else {
+        cb(null, changes);
+      }
     }
   ],
   function(err, changes) {