Merge pull request #469 from sobolevna/master

Update Authentication.php

Author: antonioribeiro

src/Services/Authentication.php

@@ -36,14 +36,13 @@ private function executeAuthMethod($method)
         foreach ($this->getAuthentication() as $auth) {
             foreach ($guards as $guard) {
                 // Call guard() if not null
-                if ($guards != 'null') {
+                if ($guard && $guard != 'null') {
                     $auth = $auth->guard($guard);
-                }
-
-                if (is_callable([$auth, $method], true, $callable_name)) {
-                    if ($data = $auth->$method()) {
-                        return $data;
-                    }
+                }                
+            }
+            if (is_callable([$auth, $method], true, $callable_name)) {
+                if ($data = $auth->$method()) {
+                    return $data;
                 }
             }
         }