attempt to index ? (a nil value)

Hey I can not figure this on out. I get a attempt to index ? (a nil value) on line 151. I have been looking at it for 2 days now and don't see a problem. Any help would be great.
Edit: The password-config file has {[1]=1, [2]="admin", [3]="password", [4]=10, [5]=120, [6]="back", [7]=10,} to start with then gets edited by the program below.

local version = 1.86
local pullEvent = os.pullEvent
local file = fs.open("/rom/programs/password-config","r")
local config_table = textutils.unserialize(file.readLine())
file.close()
--
print(config_table)
for i =1,#config_table do
print(config_table[i])
end
print("config was loaded!")
sleep(5)
--
local main = true
local programed = config_table[1]
local adminpassword = config_table[2]
local userpassword = config_table[3]
local default_attempts = config_table[4]
local timeout = config_table[5]
local rsside = config_table[6]
local waittime = config_table[7]
function UpdateUI(status)
term.clear()
term.setCursorPos(1, 1)
print("Password-Advanced v",tostring(version))
  if status < 6 then
   print("Ctrl-T is enabled when in admin setings.")
  end
  if status == 0 then
  
   print("Admin password is used to access setting.")
   term.write("Enter Admin Password:")
  end
  if status == 1 then
   print("User password is used to activate the redstone signal.")
   term.write("Enter User Password:")
  end
  if status == 2 then
   print("Limit of times you can attempted to loging in.")
   term.write("Enter Number of Times:")
  end
  if status == 3 then
   print("Time that users will be locked out after.")
   term.write("Enter Seconds:")
  end
  if status == 4 then
   print("Side that the redstone signal will come out.")
   term.write("Enter Side:")
  end
  if status == 5 then
   print("Time that redstone signal will stay high.")
   term.write("Enter Seconds:")
  end
  if status == 6 then
   term.write("Enter Password:")
  end
  if status == 7 then
   term.write("Setting Reseting!...")
  end
  if status == 8 then
   term.write("Access Granted!...")
  end
  if status == 9 then
term.write("Access Denied!...")
  end
  if status == 10 then
term.write("Exceeded Number of attempts!... (locked out)")
  end
end
function RsSignal(rs_side,wait_time)
rs.setOutput(rs_side,true)
sleep(wait_time)
rs.setOutput(rs_side,false)
end
UpdateUI(6)
while main do
if programed == 0 then -- admin settings
  os.pullEvent = pullEvent --Ctrl-t enabled
  while true do
   UpdateUI(0)
   local input = read()
	if input ~= nil then
	 adminpassword = tostring(input)
	 config_table[2] = adminpassword
	 break  
end
  end
  while true do
   UpdateUI(1)
   local input = read()
   if input ~= nil then
	userpassword = tostring(input)
config_table[3] = userpassword
	break  
   end
  end
  while true do
   UpdateUI(2)
   local input = read()
   input = tonumber(input)
	if input ~= nil then
	 default_attempts = input
  config_table[4] = default_attempts
  local current_attempts = input
  break
end  
  end
  while true do
   UpdateUI(3)
   local input = read()
   input = tonumber(input)
	if input ~= nil then
	 timeout = input
  config_table[5] = timeout
  break
end
  end
  while true do
   UpdateUI(4)
   local input = read()
   if input ~= nil then
	rsside = tostring(input)
	config_table[6] = rsside
	break  
   end
  end
  while true do
   UpdateUI(5)
   local input = read()
   input = tonumber(input)
	if input ~= nil then
	  waittime = input
   config_table[7] = waittime  
   break
end	  
  end
programed = 1
config_table[1] = 1  
os.pullEvent = os.pullEventRaw -- Ctrl-T disabled
local file = fs.open("/rom/programs/password-config","w")
file.writeLine(textutils.serialize(config_table)) --attempt to index ? (a nil value)
  --
print(config_table)
for i = 1,#config_table do
  print(config_table[i])
end
print("config was saved!")
sleep(5)
UpdateUI(6)
--
end
local input = read("*")
if current_attempts ~= 0 then
  if input ~= adminpassword then
   if input ~= userpassword then
	UpdateUI(9) --failed
	sleep(2)
	current_attempts = current_attempts - 1
	UpdateUI(6) --password
   else
	UpdateUI(8) -- urser login
	RsSignal(rsside,waittime)
	current_attempts = default_attempts
	UpdateUI(6) -- password
   end
  else
   UpdateUI(7) -- admin setings
   sleep(2)
   programed = 0
  end
else
  UpdateUI(10) -- locked out
  sleep(timeout)
  current_attempts = default_attempts
  UpdateUI(6) -- password
end

end

Please tell where line 151 is, as this lua showing does not list lines. :)/>/>

EDIT: Just try removing random characters, sometimes that will work.

file.writeLine(textutils.serialize(config_table)) –attempt to index ? (a nil value)
it is on the last screen

You can't write to the rom folder so file.open will return nil.
To solve this change the config file path to something else (like just "password-config")

greets Stiepen/Kilobyte

EDIT: yay 20th post (i know thats nearly nothing but still i'm happy now :)/>/>)

Thanks that was the main problem it is now writing nothing to the file but that i can figure out.

Thanks Again