[ERROR] (MainThread) must have users and vehicles for city 'new york' in the movr database to generate load.

movr should check which cities are available by default by searching the db. If someone loads custom city data and doesn't specify the new cities they will get this error

Start by tracing the load-generation path that raises the city error and inspect how available cities are read from the MovR database. Confirm the behavior with custom city data; done means the loader discovers database-backed cities without requiring hard-coded New York users and vehicles.

Written by the indexing model from the issue text.