Fixed: Ensure indexer errors are handled before processing response

(cherry picked from commit 76f93c8415419f0c3dab90582d47a1c9a653263c)

Closes #3628

src/NzbDrone.Core/Indexers/EzrssTorrentRssParser.cs

@@ -1,4 +1,4 @@
-using System.Linq;
+using System.Linq;
 using System.Xml.Linq;
 using NzbDrone.Common.Extensions;
 using NzbDrone.Core.Indexers.Exceptions;
@@ -16,6 +16,8 @@ namespace NzbDrone.Core.Indexers
 
         protected override bool PreProcess(IndexerResponse indexerResponse)
         {
+            base.PreProcess(indexerResponse);
+
             var document = LoadXmlDocument(indexerResponse);
             var items = GetItems(document).ToList();
 
@@ -24,7 +26,7 @@ namespace NzbDrone.Core.Indexers
                 throw new IndexerException(indexerResponse, "No results were found");
             }
 
-            return base.PreProcess(indexerResponse);
+            return true;
         }
 
         protected override long GetSize(XElement item)

src/NzbDrone.Core/Indexers/Newznab/NewznabRssParser.cs

@@ -50,6 +50,11 @@ namespace NzbDrone.Core.Indexers.Newznab
 
         protected override bool PreProcess(IndexerResponse indexerResponse)
         {
+            if (indexerResponse.HttpResponse.HasHttpError)
+            {
+                base.PreProcess(indexerResponse);
+            }
+
             var xdoc = LoadXmlDocument(indexerResponse);
 
             CheckError(xdoc, indexerResponse);

src/NzbDrone.Core/Indexers/Torznab/TorznabRssParser.cs

@@ -19,6 +19,11 @@ namespace NzbDrone.Core.Indexers.Torznab
 
         protected override bool PreProcess(IndexerResponse indexerResponse)
         {
+            if (indexerResponse.HttpResponse.HasHttpError)
+            {
+                base.PreProcess(indexerResponse);
+            }
+
             var xdoc = LoadXmlDocument(indexerResponse);
             var error = xdoc.Descendants("error").FirstOrDefault();