Add custom type serializer to manage json deserializer from database (#420)

src/core/Elsa.Core/Serialization/Converters/ExceptionConverter.cs

@@ -0,0 +1,28 @@
+using Newtonsoft.Json;
+using Newtonsoft.Json.Linq;
+using System;
+using System.Collections.Generic;
+using System.Text;
+
+namespace Elsa.Serialization.Converters
+{
+    public class ExceptionConverter : JsonConverter<Exception>
+    {
+
+        public override void WriteJson(JsonWriter writer, Exception value, JsonSerializer serializer)
+        {
+            throw new NotImplementedException("Unnecessary because CanRead is false. The type will skip the converter.");
+        }
+        public override bool CanWrite => false;
+        public override bool CanRead => true;
+
+        public override Exception ReadJson(JsonReader reader, Type objectType, Exception existingValue, bool hasExistingValue, JsonSerializer serializer)
+        {
+            //reader will throw exception if not read to end
+            var jObject = JObject.Load(reader);
+            var ex = System.Text.Json.JsonSerializer.Deserialize<Exception>(jObject.ToString());
+            return ex;
+
+        }
+    }
+}

src/persistence/Elsa.Persistence.EntityFrameworkCore/DbContexts/ElsaContext.cs

@@ -2,6 +2,7 @@ using System.Collections.Generic;
 using Elsa.Models;
 using Elsa.Persistence.EntityFrameworkCore.CustomSchema;
 using Elsa.Persistence.EntityFrameworkCore.Entities;
+using Elsa.Serialization.Converters;
 using Microsoft.EntityFrameworkCore;
 using Newtonsoft.Json;
 using Newtonsoft.Json.Linq;
@@ -29,6 +30,8 @@ namespace Elsa.Persistence.EntityFrameworkCore.DbContexts
         protected ElsaContext(DbContextOptions options) : base(options)
         {
             serializerSettings = new JsonSerializerSettings().ConfigureForNodaTime(DateTimeZoneProviders.Tzdb);
+            serializerSettings.Converters.Add(new ExceptionConverter());
+
             DbContextCustomSchema = options.GetDbContextCustomSchema();
         }