Fixed bug where FetchForWriting (the overload accepting an expected v…

…ersion) would throw an InvalidCastException when the aggregate is inline and UseIdentityMapForAggregates = true.

src/Marten/Events/Fetching/FetchInlinedPlan.cs

@@ -100,7 +100,7 @@ public async Task<IEventStream<TDoc>> FetchForWriting(DocumentSessionBase sessio
         IDocumentStorage<TDoc, TId> storage = null;
         if (session.Options.Events.UseIdentityMapForAggregates)
         {
-            storage = (IDocumentStorage<TDoc, TId>)session.Options.Providers.StorageFor<TDoc>();
+            storage = session.Options.ResolveCorrectedDocumentStorage<TDoc, TId>(DocumentTracking.IdentityOnly);
             // Opt into the identity map mechanics for this aggregate type just in case
             // you're using a lightweight session
             session.UseIdentityMapFor<TDoc>();