Event-emitter explodes when a listener tries to remove itself

[NagiNikaido]

(defpackage :remove-itself-bug
 (:use :cl :event-emitter))

(in-package :remove-itself-bug)

(defparameter *ev* (make-instance 'event-emitter))

(defun dummy-listener ()
  ())

(defun remove-itself ()
  (remove-listener *ev* :channel #'remove-itself))

(on :channel *ev* #'dummy-listener)
(on :channel *ev* #'remove-itself)
(emit :channel *ev*) ; EXPLODES!

which throws

#<THREAD tid=63927 "main thread" RUNNING {1003F801D3}>:
  Invalid index 1 for (VECTOR T 2) with fill-pointer 1,
  should be a non-negative integer below 1.

Is such removal meant not be supported? Or it seems that the actual removal should be deferred until all recursive emits have been done, considering that codes below are also possible:

(defpackage :another-situation
 (:use :cl :event-emitter))

(in-package :another-situation)

(defparameter *ev* (make-instance 'event-emitter))

(defun dummy-listener (x)
  ())

(defun remove-itself-after-3 (x)
  (format t "~a~%" x)
  (if (< x 3)
      (emit :channel *ev* (1+ x))
      (remove-listener *ev* :channel #'remove-itself-after-3)))

(on :channel *ev* #'dummy-listener)
(on :channel *ev* #'remove-itself-after-3)
(emit :channel *ev* 0) ; EXPLODES!

which prints

0
1
2
3

debugger invoked on a SB-KERNEL:INDEX-TOO-LARGE-ERROR in thread
#<THREAD tid=63927 "main thread" RUNNING {1003F801D3}>:
  Invalid index 1 for (VECTOR T 2) with fill-pointer 1,
  should be a non-negative integer below 1.