JSON with empty array

I'm working with a 3rd party REST API that returns an empty Results array when all of the data has been consumed.  "Results":[]   

This seems like it should be easy enough but it has me stumped.  I'm returning the Results to a loop that tests for Results being null which doesn't work,  but I'm not sure how to test for an empty array?

    GetActivities = (Index, access_token) =>
        let 
            Skip = Text.From(Index * RecordsPerPage),
            RawData = Web.Contents(BaseUrl,
                [
                    Headers=[
                        Authorization="Bearer " & access_token
                    ],
                    RelativePath="/crm/activity?$skip=" & Skip
                ]
            ),
            Source = Json.Document(RawData),
            Result1 = Source[Result]
            //res = try Source[Result] otherwise null,
            //Result3 = try res otherwise null
        in  Result1,

    access_token = GetToken(),
    TestRun = List.Generate ( 
        ()=>
            [Results = try GetActivities(0, access_token) otherwise null, Page = 0],
            each [Results] <> null and [Page]<5,
            each [Results = try GetActivities([Page] +1, access_token) otherwise null, Page = [Page]+1],
            each [Results]
    )
in
    TestRun

 Any pointers for a newbie would be appreciated.  Thanks in advance.