Callback not receiving errors (#72)

* Changed the error variable on the child close event so it returns the error to the callback. I left the original logic of checking for a code, if error isn’t set.

* Removed unncessary ternary statement.

* Fixed the unit test, since error is only returned if an error is passed to the callback.

* Fixed lint error.

lib/growl.js

@@ -326,15 +326,13 @@ function growl(msg, opts, callback) {
     stderr += data;
   });
 
-  child.on('close', (code) => {
-    error = error || code === 0 ? null : code;
+  child.on('close', () => {
     if (typeof fn === 'function') {
       fn(error, stdout, stderr);
     }
   });
 }
 
-
 /**
  * Expose `growl`.
  */

test.js

@@ -17,7 +17,7 @@ growl('Show pdf filesystem icon', { image: 'article.pdf' }, function(){
 })
 growl('Show pdf filesystem icon', { title: 'Use show()', image: 'article.pdf' })
 growl('here \' are \n some \\ characters that " need escaping', {}, function(error, stdout, stderr) {
-  if (error !== null) throw new Error('escaping failed:\n' + stdout + stderr);
+  if (error) throw new Error('escaping failed:\n' + stdout + stderr);
 })
 growl('Allow custom notifiers', { exec: 'echo XXX %s' }, function(error, stdout, stderr) {
   console.log(stdout);