Fixed DeepL translation when using empty text

I18N Commander/Processor/DeepL.cs

@@ -39,6 +39,9 @@ public static class DeepL
     {
         if (DEEPL_NOT_AVAILABLE)
             return string.Empty;
+
+        if (string.IsNullOrWhiteSpace(text))
+            return string.Empty;
         
         if (await AppSettings.GetDeepLMode() == SettingDeepLMode.DISABLED)
             return string.Empty;