Function is_db_disconnect 

pub fn is_db_disconnect(source: Option<&(dyn StdError + 'static)>) -> bool

True when an error’s source is a sqlx::Error::Io, which is usually the database being reset underneath a local development cluster: the caller’s cue to log its own hint and, if it keeps a connection open across ticks, reacquire one. Takes the source directly (error.source()) rather than the error, since anyhow::Error does not implement std::error::Error.