Add error handling for missing/misordered reference tables

[kelle]

It's super easy to add a reference table to the schema and then neglect to add it to the reference_table list. The order in which the reference tables are listed is also important. It would be good to have some error handling setup specifically for these two cases.

[dr-rodriguez]

Not sure how we would test for the order of lookup/reference tables, since the database won't really know which is right. But I can see that providing a clearer error message may be useful. It's tricky though, since not listing a table means it is assumed to be a data/object table and there may be many reasons why something fails to load there.