NewError is a convenient awy to create an Error-instance.

DatabaseError is when some operation related to Database, such as insert or find, goes wrong and the task cannot proceed.

InternalError represents an error when something goes wrong, and its our fault.

UserError occurs when there's an error because of user's action.

Command can be used to invoke a procedure in another service.

Document can be used to transfer data between services.

Error describes any error.

Event refers to any change in system, such as insertion of some data.

EventMeta contains the information about hydrating Aggregate-Projections.

EventStoreQuery can be used to fetch later events than the specified version.

LogEntry describes "what's currently happening" for logging purposes.