BaseIndexer: include original stack trace in OnParseError exceptions

src/Jackett/Indexers/BaseIndexer.cs

@@ -727,7 +727,7 @@ namespace Jackett.Indexers
             var spacing = string.Join("", Enumerable.Repeat(Environment.NewLine, 5));
             var fileContents = string.Format("{0}{1}{2}", ex, spacing, results);
             logger.Error(fileName + fileContents);
-            throw ex;
+            throw new Exception("Parse error", ex);
         }
 
         public override TorznabCapabilities TorznabCaps { get; protected set; }