sharepoint online – async function and await keyword not returning any value

I am trying to get the SourceID of the document in Async call using await keyword but i am not getting the value.

I am new to this concept, could anyone tell where i am doing mistake. I have added my code in below code snippet

public async GetListItems(ListTitle: string): Promise<any()> {
   debugger;
   let ListCardItemsArray: ListCardListItem() = ();
   let ListCardListItm: ListCardListItem = null;

   return new Promise<any()>(async (resolve, reject) => {
       await sp.web.lists.getByTitle(ListTitle).items.select("*").get().then((results: any) => {
           results.map((result: any) => {
               let sourceID: string;
               ListCardListItm = new ListCardListItem();
               ListCardListItm("Title") = result.Title;
               ListCardListItm("Description") = result.Description;
               ListCardListItm("DocumentURL") = result.DocumentURL;
              //here i am calling my method
               let sourceID =  this.GetSourceID("");
               ListCardListItm("SourceID") = "";
               ListCardListItm("VisioURL") = result.VisioURL;
               ListCardItemsArray.push(ListCardListItm);
           })
           console.log(ListCardItemsArray);
           resolve(ListCardItemsArray);
       }, (error: any) => {
           console.log("Error of GetListItems " + error);
           resolve(error);
       });
     });

}

public async GetSourceID(LinkURL: string) {
   let sourceID: string = "";
   try {
       let result = await sp.web.getFileByUrl("https://contosa.sharepoint.com/:u:/r/sites/Sample/SampleLibrary/Sample.vsdx?d=we836259ffe4b4f6c96ca6dd1118e6629&csf=1&web=1&e=B2w69d").select("*").get();
       sourceID = await result.UniqueId;
       console.log(sourceID);
       return sourceID;
   } catch (error) {
       console.log(error);
   }

}