Error message when trying to exit a nested machine with on instead of exit

[jamosnaim]

The error message when trying to exit a nested machine with the command "on" instead of "exit" doesn't give enough information. For example:

(machine root 
	(var out := [false])
	(state one
		(machine nested
			(state onen)
			(on goout onen->two)
			(event goout [out]))
		(onentry (spawn nested onen))
	)
	(state two)
)
(spawn root one)

shows the following error message:

In machine: nested, state two is not found

Which should be more specific for this particular issue.