Error trying to conect Power BI with TFS

Hi every body, 

I'm trying to connect to TFS, here is my code for the edvanced editor:

let
GetWorkItemIds = () =>
let
Source = Json.Document(Web.Contents("https://XXXXXX.visualstudio.com/XXXXXX/_apis/wit/wiql/a722b515-98b6-4bf7-b4a9-102c9aca1b8a")),
workItems = Source[workItems],
#"Converted to Table" = Table.FromList(workItems, Splitter.SplitByNothing(), null, null, ExtraValues.Error),
#"Expand Ids" = Table.ExpandRecordColumn(#"Converted to Table", "Column1", {"id"}, {"Work Item Id"})
in
#"Expand Ids"
in
GetWorkItemIds

With this code I get a function, but when I click to the "invoke" button, It appears the followin error:

Error inesperado en la consulta 'Consulta1'. DataFormat.Error: Se encontraron caracteres adicionales al final de la entrada JSON.
Detalles:
Value=
Position=4

Any idea?

Thanks and regards