Commented Unassigned: FilteredStream Exception [1929]

Line 263 of FilteredStream is throwing an exception because jsonTweet is null.

```
var tweetObject = _jsSerializer.Deserialize<Dictionary<string, object>>(jsonTweet);

if (!String.IsNullOrEmpty(jsonTweet))
{
```

Shouldn't this be inside the if statement?
Comments: Associated with changeset 33463: Version 0.8.3.22
Corrected a bug that incorrectly checked whetehr JsonTweet was null