Make sure spawn_as_logged_user gets an error if there was one.

lib/system/index.js

@@ -36,12 +36,12 @@ system.tempfile_path = function(filename){
   return join(system.paths.temp, filename);
 };
 
-system.spawn_as_logged_user = function(command, args, callback){
-  as_logged_user('spawn', command, args, callback);
+system.spawn_as_logged_user = function(command, args, cb){
+  as_logged_user('spawn', command, args, cb);
 }
 
-system.run_as_logged_user = function(command, args, callback){
-  as_logged_user('exec', command, args, callback);
+system.run_as_logged_user = function(command, args, cb){
+  as_logged_user('exec', command, args, cb);
 };
 
 system.get_running_user = function(){
@@ -71,12 +71,12 @@ system.get_os_info = remember(function(cb){
   });
 })
 
-var as_logged_user = function(type, bin, args, callback){
+var as_logged_user = function(type, bin, args, cb) {
 
-  var runner, command;
+  var finished, runner, command;
 
   system.get_logged_user(function(err, user){
-    if (err) return callback(err);
+    if (err) return cb(err);
 
     if (user == system.get_running_user()) {
       runner = bin;
@@ -99,15 +99,26 @@ var as_logged_user = function(type, bin, args, callback){
     }
 
     if (type == 'exec')
-      return cp.exec(runner + ' ' + command.join(' '), callback);
+      return cp.exec(runner + ' ' + command.join(' '), cb);
+
+    var done = function(e) {
+      if (finished) return;
+
+      finished = true;
+      cb(e, child);
+    }
 
     // ok, so they want spawn mode. let's fire up the command.
     var child = cp.spawn(runner, command)
 
     // set a listener on error, so if it fails the app doesn't crash!
-    child.on('error', function(err) { /* */ })
+    child.on('error', function(err) {
+      if (err.code == 'ENOENT')
+        err.message = 'ENOENT - Executable not found: ' + runner;
+
+      done(err);
+    })
 
-    // now, back to you at the studio.
-    callback(null, child);
+    process.nextTick(done)
   });
 };