Fixed some compile warnings.

src/NzbDrone.Core/Indexers/Exceptions/IndexerException.cs

@@ -9,11 +9,13 @@ namespace NzbDrone.Core.Indexers.Exceptions
         public IndexerException(IndexerResponse response, string message, params object[] args)
             : base(message, args)
         {
+            _indexerResponse = response;
         }
 
         public IndexerException(IndexerResponse response, string message)
             : base(message)
         {
+            _indexerResponse = response;
         }
 
         public IndexerResponse Response

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

@@ -124,8 +124,6 @@ namespace NzbDrone.Core.Indexers.Newznab
 
                 return new ValidationFailure(string.Empty, "Unable to connect to indexer, check the log for more details");
             }
-
-            return null;
         }
     }
 }

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

@@ -80,7 +80,7 @@ namespace NzbDrone.Core.Indexers.Newznab
         [FieldDefinition(4, Label = "Additional Parameters", HelpText = "Additional Newznab parameters", Advanced = true)]
         public string AdditionalParameters { get; set; }
 
-        public NzbDroneValidationResult Validate()
+        public virtual NzbDroneValidationResult Validate()
         {
             return new NzbDroneValidationResult(Validator.Validate(this));
         }

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

@@ -54,7 +54,7 @@ namespace NzbDrone.Core.Indexers.Torznab
     {
         private static readonly TorznabSettingsValidator Validator = new TorznabSettingsValidator();
 
-        public NzbDroneValidationResult Validate()
+        public override NzbDroneValidationResult Validate()
         {
             return new NzbDroneValidationResult(Validator.Validate(this));
         }