Power Query Accumulation that re start when text encountered ;

Hi, I have this which works using a 'try otherwise' syntax, I have been trying to re write with an 'if then else '

but have not got it working so if anyone can come up with a solution i would be interested, I have attached the workbook.

let
  alist = {"A", 2, 3, 2, 2, 3, "b", "c", 2, 3, 2, 2, "c", 2, 3, 2}
in
  List.Generate(
    () => [x = 0, y = alist{0}, z = y], 
    each [x] < List.Count(alist), 
    each [x = [x] + 1, y = alist{x}, z = try [z] + y otherwise y], 
    each [z]
  )

Richard.