流,对象文字与union不兼容

getThingFromDB: async function(id:string):Promise<EventObj|Empty>{
    const fromDB = await dao.getEvent(id);
    if(fromDB && fromDB.length){
        return fromDB[0];
    }
    return {};

}

我得到了很多流错误,比如:

return {};
       ^^ object literal. This type is incompatible with
getThingFromDB: async function(id:string):Promise<EventObj|Empty>{                                                                                
                                                  ^^^^^^^^^^^^^^ union: EventObj | Empty

或

getThingFromDB: async function(id:string):Promise<EventObj|Empty>                                                                                      
                                                  ^^^^^^^^ property `id`. Property not found in
return {};
       ^^ object literal

declare type EventObj = {
    id:string,
    name:string,
    urlName:string
};

declare type Empty = {||};

我错过了什么?如何正确地满足这些错误。