Exceptions thrown from SinkTask::close shadow other exceptions

If an exception is thrown from SinkTask::close, the exception will shadow any other previous exception, because SinkTask::close is called from within a finally block.

Steps to reproduce:

1. Throw an exception from SinkTask::start or SinkTask::put 
2. Throw an exception from SinkTask::close

Expected behavior:

• All exceptions are visible in separate log messages
• The error from SinkTask::start or SinkTask::put is logged as the exception that caused the task to stop.

Actual behavior:

• The exception from SinkTask::close is logged as the exception that caused the task to stop.
• The exceptions from either SinkTask::start or SinkTask::put are swallowed and don't appear in the logs at all.