Reads the database's stamped schema version from schema_meta, or null when that table is
absent (an un-migrated or pre-versioning database). Any query failure also reads as null, so
an unreachable or unauthorized database looks un-migrated rather than throwing here. The
composition layer passes the result to its schema assert to fail fast on a schema that has
drifted from this code.
Reads the database's stamped schema version from
schema_meta, ornullwhen that table is absent (an un-migrated or pre-versioning database). Any query failure also reads asnull, so an unreachable or unauthorized database looks un-migrated rather than throwing here. The composition layer passes the result to its schema assert to fail fast on a schema that has drifted from this code.