App crashes if you try to stream without selecting a sector

If you tap "STREAM" (using either internal sensors or Bluetooth platforms) without selecting a sector, Field Day crashes. (The expected behavior is that it does not crash...)

There are at least two possible solutions:

• Pre-populate the site and sector fields with default values. This already appears to happen for the site field, although it does not follow up by populating the sector dropdown with a list of sectors associated with that site.
• On user tap of "STREAM", check for empty values in site and sector. Display a message prompting the user to select a value for each empty field. This adds friction but gives the user more transparent control. Similar logic exists already for "SAMPLE", which displays a message prompting the user to enter a spot number before taking a reading, if they have not already done so.