List Generate, accumulation which re starts when at text value

Hi, 
so   List.Generate to accumulate wiith text , i have been  trying various accumulations  with a mixture of number and text , 
so fist  inlcude the text ;  { 2,2,3, "a", 3,3 } = { 2,4, 7, "a", 10, 13}  , then skip  { 2,4, 7, 7, 10, 13} and last re start { 2,4, 7, "a2, 3,6} 
so i have used a try otherwise for the  re start but would like to  see if there is another way to achiee this , the first two 
i jut put in for interest, they are not a problem.

accumulate; 

let
  alist = {"a", 2, 3, 2, 2, "b", "c", 2, 3, 2, "d", 2, 2, 2},
  result = List.Generate(
    () => [x = 0, y = alist{0}, z = if Value.Is(y, type number) then y else 0],
    each [x] < List.Count(alist),
    each [x = [x] + 1, y = alist{x}, z = if Value.Is(y, type number) then [z] + y else [z]],
    each if Value.Is([y], type number) then [z] else [y]
  )
in
  result


skip ;

let
  alist = {"a", 2, 3, 2, 2, "b", "c", 2, 3, 2, "d", 2, 2, 2},
  result = List.Generate(
    () => [x = 0, y = alist{0}, z = if Value.Is(y, type number) then y else 0],
    each [x] < List.Count(alist),
    each [x = [x] + 1, y = alist{x}, z = if Value.Is(y, type number) then [z] + y else [z]],
    each [z]
  )
in
  result


re start ;


let
  alist = {"a", 2, 3, 2, 2, "b", "c", 2, 3, 2, "d", 2, 2, 2},
  result = 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]
  )
in
  result

So trying to do is get a re - start without  try / otherwise;,  i
I have been trying things like this  

= List.Generate( ()=> 
[x = 0 ,y = alist {0} , z = y ]  , 
each [x] < List.Count( alist ), 
each [  x = [x] + 1,  y = alist {x}, z = 
if Value.Is( y, type number) then [y] + y else y] ,
each [z] )

but so far i have not come up wiht a method , any suggestions ? 

Richard.