Fix hard crash of Revit on Dynamo crash

### Issue

Right now, in the majority of cases, a hard crash of Dynamo will also cause a hard crash of Revit.  

In the `Dispatcher` exception in DynamoRevit, we use a reference to `RevitDynamoModel`.  This reference has already been set to `null` in line 452 of `DynamoRevit.`  Therefore, we should avoid referencing it in the finally block inside of this handler.  

In fact, we should avoid doing anything complex in this block.  

### Fix

I removed the erroneous call to `Logger.Dispose` in the finally block.  This is already called `OnDynamoViewClosed`.  

### Reviewers

- [x] @ikeough 
- [x] @Benglin