Fixed DeepL translation when using empty text

I18N Commander/Processor/DeepL.cs

@@ -40,6 +40,9 @@ 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;