Properly throw deserializer errors

[derekantrican]

If exceptions are thrown within the Error handler, they will ultimately be thrown as

System.InvalidOperationException: Current error context error is different to requested error

According to the example on the Newtonsoft.Json website errors should be captured, marked as Handled, then accessed after the deserializing process.

This will provide accurate error feedback to users of this library and prevent confusion like in #44