Provide more useful errors for user on a failure to access navmesh.db
To avoid situations like this. The error message is confusing for not an OpenMW developer. Users need some kind of advice what to do about it like to remove the navmesh.db file. Although it's not just about the error message change. The are multiple levels of abstraction it goes through loosing some context of the way up. The error is originated from here. Maybe need to avoid using exceptions and return error code using sqlite3_errcode
to get SQLite3 specific one and give advice on a higher level.