Error fetching results from a BigQuery asynchronous call in 0.19.0

[georgegiovanni]

Referring to the doc, calling QueryResults.fetch_data raises an exception since self.name is None:

if self.name is None:
 raise ValueError("Query not yet executed: call 'run()'")

However, if QueryResults.run is called, an exception is also raised since self._job already exists:

if self._job is not None:
 raise ValueError("Query job is already running.")

[tseaver]

@georgegiovanni Thanks for the report!