Обработка ошибок

Sub god()
 
On Error Resume Next            ' при ошибке продолжать
Dim lists As Byte
Dim rez As Single, sum As Single
'On Error GoTo jok            ' как вариант переход при ошибке
    For lists = 1 To 12
    MsgBox lists
  ' If Worksheets(lists) Is Nothing Then GoTo jok   ' И так пробовал
     rez = Worksheets(lists).cells(16, 3).Value        'Здесь останов, если индекс(lists) > существующих листов
    MsgBox rez
        sum = sum + rez
   '     MsgBox sum
    Next lists
    jok:
     MsgBox sum
End Sub

Dim ws As Worksheet, sum#
For Each ws In Worksheets
    sum = sum + ws.[C16]
Next

   For Each sh In ThisWorkbook.Sheets
       rez = sh.Cells(16, 3).Value 
       MsgBox rez
       sum = sum + rez
   Next sh
   MsgBox sum

dim sh as worksheet
dim sum,rez
sum=0
on error resume next
For Each sh In ThisWorkbook.Sheets
       rez=0
       rez = sh.Cells(16, 3).Value 
       debug.print sh.name,rez
       sum = sum + rez
Next sh
MsgBox sum

dim sh as worksheet
dim sum,rez,sname
sum=0
on error resume next
For Each sh In ThisWorkbook.Sheets
       rez=0
       sname=sh.name
if sname like "*2016" then
       rez = sh.Cells(16, 3).Value 
       debug.print sh.name,rez
       sum = sum + rez
endif
Next sh
MsgBox sum

For lists = 1 To Worksheets.Count

if sname like "*2016" then

On Error Resume Next
For i = 1 To 12
    Set ws = Worksheets(i)
    If Err.Number = 0 Then
       res = ws.[C13]: MsgBox res
    Else
       res = 0: MsgBox res
    End If
Next