(1) what behavior you expected
(2) what behavior you observed
(3) and how we can reproduce the issue.
Debugger entered--Lisp error: (void-function magit--checkout)
magit--checkout("stdlib-serialization")
#<subr magit-imerge-abort>()
apply(#<subr magit-imerge-abort> nil)
#f(compiled-function (fn &rest args) #<bytecode 0x3006706562954d7>)(#<subr magit-imerge-abort>)
apply(#f(compiled-function (fn &rest args) #<bytecode 0x3006706562954d7>) #<subr magit-imerge-abort> nil)
(lambda (fn &rest args) (interactive #f(compiled-function (spec) #<bytecode -0x9e249f3b72d570d>)) (apply '#f(compiled-function (fn &rest args) #<bytecode 0x3006706562954d7>) fn args))(#<subr magit-imerge-abort>)
apply((lambda (fn &rest args) (interactive #f(compiled-function (spec) #<bytecode -0x9e249f3b72d570d>)) (apply '#f(compiled-function (fn &rest args) #<bytecode 0x3006706562954d7>) fn args)) #<subr magit-imerge-abort> nil)
magit-imerge-abort()
funcall-interactively(magit-imerge-abort)
command-execute(magit-imerge-abort)