后台：修复活动创建bug

gm-server/app/service/Activity.ts

@@ -31,11 +31,9 @@ export default class Activity extends Service {
     public async checkActivityEditable(activityId: number) {
         let now = new Date();
         let activity = await ActivityModel.findActivity(activityId);
-        if(!activity) {
-            return this.ctx.service.utils.resResult(STATUS.ACTIVITY_MISSING);
-        }
+
         if(this.app.config.env == 'production') {
-            if(activity.beginTime < now && activity.endTime > now) {
+            if(!activity || (activity.beginTime < now && activity.endTime > now)) {
 
                 if(activity.type == ACTIVITY_TYPE.SIGN_IN || activity.type == ACTIVITY_TYPE.SIGN_IN_VIP) {
                     // 签到活动的不显示期内也可以编辑