typo: Fix typo in err_map key
typo: Fix typo in err_map key

Change "MACHINE_DOES_NOT_EXST" to "MACHINE_DOES_NOT_EXIST".

Please disregard if not valid.
warmchang/minikube,dlorenc/minikube,dlorenc/minikube,warmchang/minikube,kubernetes/minikube,kubernetes/minikube,kubernetes/minikube,dlorenc/minikube,dalehamel/minikube,warmchang/minikube,warmchang/minikube,dlorenc/minikube,kubernetes/minikube,dalehamel/minikube,warmchang/minikube,warmchang/minikube,dlorenc/minikube,dalehamel/minikube,kubernetes/minikube,warmchang/minikube,kubernetes/minikube,dlorenc/minikube,dlorenc/minikube,dlorenc/minikube,kubernetes/minikube