Handle null temperature data

[alanisaac]

• The javascript code gets weather data that has possibly null temperature data, possibly because the data source does not have data for today's temperatures.
• The rules engine team expects temperature data to exist.

Figure out what to do here. cc: @plocket @thadk

[AdamFinkle]

For now, the rules engine team has chosen to throw an exception when any null temperature value is given. We expect this exception to occur only if the billing period ended in the past five days because open-meteo splits its weather data api into a 'historical' portion, which excludes the past five days, which it offers in a 'forecast' portion. The javascript could handle this exception by fetching the missing temperature data from the 'forecast' portion, combining it with the 'historical' data, and sending the combined data to the rules engine.