Unhelpful error when the migrations table doesn't exist

This is the error message when a user boots a new lucky app with a correctly configured database url which points to an empty database (no migrations table):

2022-03-04 20:01:41.619 UTC [68] ERROR:  relation "migrations" does not exist at character 16
2022-03-04 20:01:41.619 UTC [68] STATEMENT:  SELECT id FROM migrations WHERE version = $1
web          | Unhandled exception: relation "migrations" does not exist (PQ::PQError)
web          | 
web          |                                              
web          |    🎉 App running at http://127.0.0.1:3001   
web          |                                              
web          | 

web          |   from lib/pg/src/pq/connection.cr:203:7 in 'handle_error'
web          |   from lib/pg/src/pq/connection.cr:186:7 in 'handle_async_frames'
web          |   from lib/pg/src/pq/connection.cr:162:7 in 'read'
web          |   from lib/pg/src/pq/connection.cr:157:7 in 'read'
web          |   from lib/pg/src/pq/connection.cr:414:31 in 'expect_frame'
web          |   from lib/pg/src/pq/connection.cr:413:5 in 'expect_frame'
web          |   from lib/pg/src/pg/statement.cr:18:5 in 'perform_query'
web          |   from lib/db/src/db/statement.cr:93:9 in 'perform_query_with_rescue'
web          |   from lib/db/src/db/statement.cr:80:7 in 'query:args'
web          |   from lib/db/src/db/pool_statement.cr:29:30 in 'query:args'
web          |   from lib/db/src/db/query_methods.cr:46:7 in 'query:args'
web          |   from lib/db/src/db/query_methods.cr:61:7 in 'query_one?:as'
web          |   from lib/avram/src/avram/migrator/migration.cr:67:7 in 'migrated?'
web          |   from lib/avram/src/avram/migrator/migration.cr:62:6 in 'pending?'
web          |   from lib/avram/src/avram/migrator/runner.cr:200:32 in 'pending_migrations'
web          |   from lib/avram/src/avram/migrator/runner.cr:172:9 in 'ensure_migrated!'
web          |   from src/start_server.cr:7:3 in '__crystal_main'
web          |   from /usr/share/crystal/src/crystal/main.cr:110:5 in 'main_user_code'
web          |   from /usr/share/crystal/src/crystal/main.cr:96:7 in 'main'
web          |   from /usr/share/crystal/src/crystal/main.cr:119:3 in 'main'
web          |   from __libc_start_main
web          |   from _start
web          |   from ???

As far as I can tell, that message comes from start_server.cr which is attempting to check to see that the database is up to date. Perhaps it should check to see if the migrations table exists before asking that question, and provide some helpful feedback if not.

Start at src/web_app_skeleton/src/start_server.cr.ecr and trace the migration check that produces the missing migrations-table error. Reproduce startup against an empty database, then define a more helpful failure message for that condition; done means the empty-database case no longer reports only the raw database error.