Is it one redundant code?

[falconray0704]

Hi,
Firstly, thanks for you work, it's a great job.
I have one question in the following code:
*In fsm.go line:324 function: func (f FSM) Event(event string, args ...interface{}) error

// Perform the rest of the transition, if not asynchronous.
f.stateMu.RUnlock()
err = f.doTransition()
f.stateMu.RLock()
if err != nil {
return InternalError{}
}

Per the comment in line:319 "// Perform the rest of the transition, if not asynchronous.".
I think that means in sync mode would run the following code.
So, InternalError{} should come from f.doTransition()

But, In function:
// doTransition wraps transitioner.transition.
func (f *FSM) doTransition() error {
return f.transitionerObj.transition(f)
}

"f.transitionerObj" is "transitionerStruct"

Then transitionerStruct's transition() should be called.

But In this function, the only way return error is "f.transition == nil"
func (t transitionerStruct) transition(f *FSM) error {
if f.transition == nil {
return NotInTransitionError{}
}
f.transition()
f.transition = nil
return nil
}

But, per the previous code, if "f.doTransition()" can be invoked, "f.transition" have no way to get nil.

Is it one redundant code? I'm confuse, I hope I could get your help to confirm did I miss something or not.