Error hierarchy for State machine

[DmiSergeev]

Motivation

Currently, a significant amount of State machine code uses String as left part of Either/EitherT – for handling various errors and exceptional cases. It includes both creation of new error messages for some edge cases and wrapping caught exceptions. It makes the current code not expressive enough and not clean.

Proposition

A carefully designed error class/object hierarchy is required. StateMachineError as the root class has already applied for the transaction invocation and other statemachine part. VM project error hierarchy can be used as a reference.

[alari]

Closed as obsolete