HMI: Fix hmi_status_helper exception when calling request.json().
HMI: Fix hmi_status_helper exception when calling request.json().

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