Add error resilient context store

Author: msft-shahins

CSharp/Library/Dialogs/Conversations.cs

@@ -97,7 +97,8 @@ internal static BinaryFormatter MakeBinaryFormatter(IServiceProvider provider)
             };
             var formatter = Conversation.MakeBinaryFormatter(provider);
 
-            IDialogContextStore store = new DialogContextStore(formatter);
+            IDialogContextStore contextStore = new DialogContextStore(formatter);
+            IDialogContextStore store = new ErrorResilientDialogContextStore(contextStore);
 
             IDialogContext context;
             if (!store.TryLoad(botData.PerUserInConversationData, BlobKey, out context))

CSharp/Library/Dialogs/DialogContextStore.cs

@@ -88,4 +88,33 @@ void IDialogContextStore.Save(IDialogContext context, IBotDataBag bag, string ke
             bag.SetValue(key, blobNew);
         }
     }
+
+    public sealed class ErrorResilientDialogContextStore : IDialogContextStore
+    {
+        private readonly IDialogContextStore store;
+
+        public ErrorResilientDialogContextStore(IDialogContextStore store)
+        {
+            SetField.NotNull(out this.store, nameof(store), store);
+        }
+
+        public void Save(IDialogContext context, IBotDataBag bag, string key)
+        {
+            this.store.Save(context, bag, key);
+        }
+
+        public bool TryLoad(IBotDataBag bag, string key, out IDialogContext context)
+        {
+            try
+            {
+                return this.store.TryLoad(bag, key, out context);
+            }
+            catch (Exception)
+            {
+                // exception in loading the serialized context data
+                context = null;
+                return false;
+            }
+        }
+    }
 }