Misc Fixes

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

@@ -16,7 +16,7 @@ namespace NzbDrone.Core.Indexers.Newznab
         private readonly INewznabCapabilitiesProvider _capabilitiesProvider;
 
         public override string Name => "Newznab";
-        public override string BaseUrl => Settings.BaseUrl;
+        public override string BaseUrl => GetBaseUrlFromSettings();
         public override bool FollowRedirect => true;
 
         public override DownloadProtocol Protocol => DownloadProtocol.Usenet;
@@ -40,6 +40,18 @@ namespace NzbDrone.Core.Indexers.Newznab
             return new NewznabRssParser(Settings);
         }
 
+        public string GetBaseUrlFromSettings()
+        {
+            var baseUrl = "";
+
+            if (Definition == null || Settings == null || Settings.Categories == null)
+            {
+                return baseUrl;
+            }
+
+            return Settings.BaseUrl;
+        }
+
         public IndexerCapabilities GetCapabilitiesFromSettings()
         {
             var caps = new IndexerCapabilities();