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.