Close #69 update error level when user can't register

src/User/Service/UserRegisterService.php

@@ -78,7 +78,7 @@ class UserRegisterService implements ServiceInterface
             return true;
         } catch (Exception $e) {
             $transaction->rollBack();
-            $this->logger->log($e->getMessage(), Logger::LEVEL_WARNING);
+            $this->logger->log($e->getMessage(), Logger::LEVEL_ERROR);
 
             return false;
         }