simple

var (
	// ErrUnknownEntityType indicates no workflow definition exists for the requested entity.
	ErrUnknownEntityType = errors.New("workflow: entity type not registered")
	// ErrInvalidTransition indicates the requested transition is not allowed.
	ErrInvalidTransition = errors.New("workflow: transition not allowed")
	// ErrMissingTransition indicates neither a transition name nor target state were supplied.
	ErrMissingTransition = errors.New("workflow: transition name or target state required")
	// ErrNilEntityID signals input validation failure.
	ErrNilEntityID = errors.New("workflow: entity id required")
	// ErrDefinitionStatesRequired indicates a definition is missing states.
	ErrDefinitionStatesRequired = errors.New("workflow: definition requires at least one state")
	// ErrStateNameRequired indicates a workflow state is missing its name.
	ErrStateNameRequired = errors.New("workflow: state name required")
	// ErrDuplicateState indicates duplicate workflow state names were declared.
	ErrDuplicateState = errors.New("workflow: duplicate state")
	// ErrTransitionStateUnknown indicates a transition references an unknown state.
	ErrTransitionStateUnknown = errors.New("workflow: transition references unknown state")
	// ErrDuplicateTransition indicates the same transition name is declared multiple times for a state.
	ErrDuplicateTransition = errors.New("workflow: duplicate transition for state")
	// ErrTerminalState indicates a transition was attempted from a terminal state.
	ErrTerminalState = errors.New("workflow: terminal state reached")
	// ErrGuardAuthorizerRequired indicates a guard was present but no authorizer was configured.
	ErrGuardAuthorizerRequired = errors.New("workflow: guard authorizer required")
)