Error handling in migration to new quality

src/NzbDrone.Common/Serializer/Json.cs

@@ -41,15 +41,22 @@ namespace NzbDrone.Common.Serializer
             return JsonConvert.DeserializeObject(json, type, SerializerSetting);
         }
 
-        public static T TryDeserialize<T>(string json) where T : new()
+        public static bool TryDeserialize<T>(string json, out T result) where T : new()
         {
             try
             {
-                return Deserialize<T>(json);
+                result = Deserialize<T>(json);
+                return true;
             }
             catch (JsonReaderException ex)
             {
-                return default(T);
+                result = default(T);
+                return false;
+            }
+            catch (JsonSerializationException ex)
+            {
+                result = default(T);
+                return false;
             }
         }
 

src/NzbDrone.Core/Datastore/Migration/036_update_with_quality_converters.cs

@@ -14,10 +14,12 @@ namespace NzbDrone.Core.Datastore.Migration
     {
         protected override void MainDbUpgrade()
         {
-            Alter.Table("QualityProfiles").AddColumn("Items").AsString().Nullable();
+            if (!Schema.Table("QualityProfiles").Column("Items").Exists())
+            {
+                Alter.Table("QualityProfiles").AddColumn("Items").AsString().Nullable();
+            }
 
             Execute.WithConnection(ConvertQualityProfiles);
-
             Execute.WithConnection(ConvertQualityModels);
         }
         
@@ -80,7 +82,12 @@ namespace NzbDrone.Core.Datastore.Migration
                         var id = qualityModelReader.GetInt32(0);
                         var qualityJson = qualityModelReader.GetString(1);
 
-                        var quality = Json.Deserialize<QualityModel>(qualityJson);
+                        QualityModel quality;
+
+                        if (!Json.TryDeserialize<QualityModel>(qualityJson, out quality))
+                        {
+                            continue;
+                        }
 
                         var qualityNewJson = qualityModelConverter.ToDB(quality);
 

src/NzbDrone.Core/Download/Clients/Sabnzbd/SabCommunicationProxy.cs

@@ -31,10 +31,10 @@ namespace NzbDrone.Core.Download.Clients.Sabnzbd
             var action = String.Format("mode=addfile&cat={0}&priority={1}", category, priority);
 
             request.AddFile("name", ReadFully(nzb), title, "application/x-nzb");
-            
-            var response = Json.TryDeserialize<SabAddResponse>(ProcessRequest(request, action));
 
-            if (response == null)
+            SabAddResponse response;
+
+            if (!Json.TryDeserialize<SabAddResponse>(ProcessRequest(request, action), out response))
             {
                 response = new SabAddResponse();
                 response.Status = true;
@@ -87,9 +87,9 @@ namespace NzbDrone.Core.Download.Clients.Sabnzbd
                 throw new ApplicationException("Unable to connect to SABnzbd, please check your settings");
             }
 
-            var result = Json.TryDeserialize<SabJsonError>(response.Content);
+            SabJsonError result;
 
-            if (result == null)
+            if (!Json.TryDeserialize<SabJsonError>(response.Content, out result))
             {
                 //Handle plain text responses from SAB
                 result = new SabJsonError();