Github user nsuke commented on the issue:
https://github.com/apache/thrift/pull/1289
It's more of a usability problem.
The problem is that the user is passing a non-`byte` instance to
`writeBinary`. It's basically the same error as when you pass str `'42'` (not
integer `42`) to writeI32.
We can put this kind of conversion to any `writeXxx` functions including
`writeBinary`. A downside would be potential surprises when users didn't
actually intend to do that.---
