control: fix msg not ready nullptr access crash.
control: fix msg not ready nullptr access crash.

jinghaomiao/apollo,ycool/apollo,jinghaomiao/apollo,xiaoxq/apollo,ycool/apollo,jinghaomiao/apollo,jinghaomiao/apollo,xiaoxq/apollo,ApolloAuto/apollo,ApolloAuto/apollo,ycool/apollo,jinghaomiao/apollo,ycool/apollo,xiaoxq/apollo,ApolloAuto/apollo,wanglei828/apollo,jinghaomiao/apollo,wanglei828/apollo,ycool/apollo,wanglei828/apollo,xiaoxq/apollo,wanglei828/apollo,xiaoxq/apollo,ApolloAuto/apollo,ApolloAuto/apollo,xiaoxq/apollo,wanglei828/apollo,wanglei828/apollo,ycool/apollo,ApolloAuto/apollo