have clear error messages in console when expected column is missing

[galiat]

As we try try to support other group's datasets we want to make it as easy as possible to troubleshoot why their sheet isn't working with our code.

Add console statements for any important column names that are missing. If you need help determining what is an important column name, ask in the slack channel.

We may in the future make this even more user friendly with a helpful real UI but for now lets stick to what is most simple.

[acharliekelly]

There should be console messages for debugging, but also some kind of user feedback beyond the infinite progress circle, so the user knows that the app is broken and they should contact whoever the admin is and let them know to stop changing column names

[acharliekelly]

BTW, for whomever is working on this issue: Tabletop has a 'debug' property that will give verbose messages about what it's doing. Could probably help with figuring out what's up with bad column names