Implement user level error handler

[jvalkeal]

In a various stages a user level code is executed like actions, listeners, annotated methods etc. We've been trying to catch and log these errors so that ssm would continue to operate without causing a breakage.

However at some point we should try to propagate these error into a user level error handler so that user can choose if ssm should continue its own operations. It is kinda a choice if ssm should enter internal error state or not.

[aldib]

This is a major issue. A very common modelling pattern in process design is to have an "Error Superstate" that can be transitioned to from any other non final states with an exit transition to a deep history. Usually a generic error handler catches exception and and broadcast an event to transition to the "Error Superstate". Handling errors with a specific state simplifies the calculation of KPI, usage of priority queues, etc..
I tried to implement the above using

 m.getStateMachineAccessor().doWithAllRegions((a)->{
    a.addStateMachineInterceptor(new StateMachineInterceptorAdapter<String,String>(){
        @Override
        public Exception stateMachineError(StateMachine stateMachine, Exception exception) {
            //do something
        }
    });
});

but DefaultStateMachineExecutor:210 swallows the exception and the interceptor is never called.

I attached a test case.

spring-statemachine-bug.zip

[dayre]

We're trying to use the sync task exec and deal with error handling caused within an action. It looks impossible until the DefaultStateMachineExecutor.handleTriggerTrans() no longer swallows the exceptions.