Error when trying to load a record that exceeds the max message size.

[jeffadair]

Describe the bug
When trying to load a record that exceeds ..., this error is thrown.

Traceback (most recent call last): File "/usr/lib64/python3.7/threading.py", line 926, in _bootstrap_inner self.run() File "stream-producer.py", line 2040, in run self.print(self.evaluate(message)) File "stream-producer.py", line 1860, in print record_id = record.get(self.record_identifier) AttributeError: 'str' object has no attribute 'get'

This is one place where the bug exists. There are others: https://github.com/Senzing/stream-producer/blame/master/stream-producer.py#L1858-L1860

Make sure to handle if self.record_identifier doesn't exist.

To Reproduce
Load a record that is too big.