remove -1 backupfileslimit message

app/UI/BackupJob/Forms/UpdateForm.php

@@ -50,6 +50,10 @@ class UpdateForm extends BaseForm implements ClientArea
         }else if($this->getWhmcsConfigOption(ConfigurableOption::BACKUPS_FILES) == "-1"){
             $backupFilesLimit = null;
         }
+        if ($backupFilesLimit == "-1")
+        {
+            $backupFilesLimit = null;
+        }
         if ($this->configuration()->isBackupRouting() && $backupFilesLimit)
         {
             sl("lang")->addReplacementConstant("backupFilesLimit" , $backupFilesLimit);