Java Exeption

rednet.open("back")

while true do
  id,request = rednet.receive()
  if request == "balance" then
    id,name = rednet.receive(.5)
    id,pass = rednet.receive(.5)
    if pass ~= nil or name ~= nil then
      local account = fs.open("Accounts/"..name,"r")
      local accountInfo = {}
      for line in account.readLine do
        accountInfo[#accountInfo+1] = line
      end
      account.close()
      if accountInfo[1] == pass then
        rednet.send(id,accountInfo[2])
      end
    end
  elseif request == "transfer" then
    id,name = rednet.receive(.5)
    id,pass = rednet.receive(.5)
    id,to = rednet.receive(.5)
    id,ammount = rednet.receive(.5)
    if name ~= nil or pass ~= nil or to ~= nil or ammount ~= nil then
      local account = fs.open("Accounts/"..name,"r")
      local accountInfo = {}
      for line in account.readLine do
        accountInfo[#accountInfo+1] = line
      end
      account.close()
      if pass == accountInfo[1] then
        if fs.exists("Accounts/"..to) == true then
          local tmpPerson = fs.open("Accounts/"..to,"r")
          local personInfo = {}
          for line in tmpPerson.readLine do
            personInfo[#personInfo+1] = line
          end
          tmpPerson.close()
          if tonumber(accountInfo[2]) >= ammount then
            personInfo[2] = tonumber(personInfo[2])+ammount
            local person = fs.open("Accounts/"..to,"w")
            for i=0, #personInfo do
              person.writeLine(personInfo[i])
            end
            local account = fs.open("Accounts/"..name,"w")
            accountInfo[2] = tonumber(accountInfo[2])-ammount
            for i=0, #accountInfo do
              person.writeLine(accountInfo[i])
            end
            account.close()
            person.close()
          end
        end
      end
    end
  end
end