Missing fields produce Altair errors

[aggFTW]

I was doing the following hive query when I discovered an error:

%hive SELECT * FROM hivesampletable WHERE deviceplatform = 'Android'

With the following pandas df:

records_text = '{"clientid":"8","querytime":"18:54:20","market":"en-US","deviceplatform":"Android","devicemake":"Samsung","devicemodel":"SCH-i500","state":"California","country":"United States","querydwelltime":13.9204007,"sessionid":0,"sessionpagevieworder":0}\n{"clientid":"23","querytime":"19:19:44","market":"en-US","deviceplatform":"Android","devicemake":"HTC","devicemodel":"Incredible","state":"Pennsylvania","country":"United States","sessionid":0,"sessionpagevieworder":0}'
json_array = "[{}]".format(",".join(records_text.split("\n")))
import json
d = json.loads(json_array)
result = pd.DataFrame(d)
result

the NaN for querydwelltime produces the following error:

Javascript error adding output!
TypeError: Cannot read property 'prop' of undefined
See your browser Javascript console for more details.

The vegalite spec produced by Altair is:

{'config': {'width': 600, 'gridOpacity': 0.08, 'gridColor': u'black', 'height': 400}, 'marktype': 'point', 'data': {'formatType': 'json', 'values': [{u'deviceplatform': u'Android', u'devicemodel': u'SCH-i500', u'country': u'United States', u'sessionpagevieworder': 0, u'state': u'California', u'clientid': u'8', u'sessionid': 0, u'querytime': u'18:54:20', u'devicemake': u'Samsung', u'market': u'en-US', u'querydwelltime': 13.9204007}, {u'deviceplatform': u'Android', u'devicemodel': u'Incredible', u'country': u'United States', u'sessionpagevieworder': 0, u'state': u'Pennsylvania', u'clientid': u'23', u'sessionid': 0, u'querytime': u'19:19:44', u'devicemake': u'HTC', u'market': u'en-US', u'querydwelltime': nan}]}}

For commentary and possible fixes, this issue is tracked by lightning renderer in:
lightning-viz/lightning-python#34

We might need to address this in Altair too.

cc @ellisonbg @mathisonian

[aggFTW]

Closed for now, as we are not using Altair anymore.