ComputerCraft Help Line 91 Attempt to call Nil????

--]] File: Manager [[--
term.clear()
term.setBackgroundColor(colors.blue)
term.setTextColor(colors.white)
term.clear()
term.setCursorPos(1,1)
write "File Command: "
cmd = read()
if cmd == "List" or cmd == "list" or cmd == "ls" or cmd == "edit" or cmd == "Edit" or cmd == "create" or cmd == "Create" or cmd == "exit()" then
----------------------------------------------------------
if cmd == "List" or cmd == "list" or cmd == "ls" then
print "Files: "
local bAll = false
local tArgs = { ... }
if #tArgs > 0 and tArgs[1] == "all" then
bAll = true
end

local tPrograms = shell.programs( bAll )
textutils.pagedTabulate( tPrograms )
print "Press Any Key To Continue."
event = os.pullEvent()
shell.run("manager")
---------------------------------------------------
function ED()
term.clear()
term.setCursorPos(1,1)
term.setBackgroundColor(colors.blue)
term.setTextColor(colors.white)
term.clear()
write "Edit: "
ed = read()
if ed == "exit()" then
shell.run("gui")
elseif ed == "back" then
shell.run("manager")
elseif fs.exists(ed) then
shell.run("edit",ed)
edit()
else
print("File: "..ed.." Doesnt Exist")
sleep(3)
edit()
end
end
end
-------------------------------------------------
function create()
term.setBackgroundColor(colors.blue)
term.setTextColor(colors.white)
term.clear()
term.setCursorPos(1,1)
write "CreateFile:  "
cr = read()
if cr == "exit()"then
shell.run("gui")
elseif cr == "back" then
shell.run("manager")
elseif fs.exists(cr) then
print("Error File:"..cr.." Already Exists")
sleep(2)
create()
else
print("Create File:"..cr.." ?")
print " [YES] - [NO] "
local event, button, X, Y = os.pullEventRaw()
while true do
if event == "mouse_click" then
  --]] yes selected [[--
  if X >=1 and X <=7 and Y == 3 and button == 1 then
  print "Creating File..."
  sleep(2)
  file = fs.open(cr,"w")
  file.write("--]] File: "..cr.." [[--")
  file.close()
  print "File Created"
  sleep(2)
  create()
  --]] no selected [[--
  elseif X >=9 and X <=14 and Y == 3 and button == 1 then
  print "File Creation Canceled"
  sleep(2)
  create()
  end
  end
  end
  end
  end
---------------------------------------------------
if cmd == "edit" or cmd == "Edit" then
ED()
end

if(cmd == "create" or cmd == "Create") then
create()
end
-----------------------------------------------------
else
print "Error Not A Command Commands are edit , create or list"
sleep(2)
shell.run("manager")
end