Function zebra_state::service::finalized_state::disk_format::upgrade::add_subtrees::subtree_format_calculation_pre_checks

pub fn subtree_format_calculation_pre_checks(db: &ZebraDb) -> Result<(), String>

Quickly check that the first calculated subtree is correct.

This allows us to fail the upgrade quickly in tests and during development, rather than waiting ~20 minutes to see if it failed.

This check runs the first subtree calculation, but it doesn’t read the subtree data in the database. So it can be run before the upgrade is started.