While...Do Error

function checkfortree(i)
  turtle.select(16)
  sleep(5)
  local i = 0
  if (turtle.compare() == true) then
    i = 1
    return i
  end
end

function minelayer()
  turtle.digUp()
  turtle.up()
  turtle.dig()
  turtle.forward()
  turtle.turnRight()
  turtle.dig()
  turtle.forward()
  turtle.turnRight()
  turtle.dig()
  turtle.forward()
  turtle.turnRight()
  turtle.forward()
  turtle.turnRight()
end

function minetree()
  local i = 0
  local hight = 0
  turtle.dig()
  turtle.forward()
  turtle.dig()
  turtle.forward()
  turtle.turnRight()
  turtle.dig()
  turtle.forward()
  turtle.turnRight()
  turtle.dig()
  turtle.forward()
  turtle.turnRight()
  turtle.forward()
  turtle.turnRight()
  while (i == 0) do
    minelayer()
    hight = hight + 1
    turtle.select(16)
    if (turtle.compareUp() == false) then
      while (hight ~= 0) do
        turtle.down()
        hight = hight - 1
      end
      turtle.back()
      i = 1
    end
  end
end

function dumpitems()
  local i = 0
  local f = 1
  turtle.turnLeft()
  while (f < 14) do
  turtle.select(f)
    if (turtle.compareTo(16) == true) then
      turtle.drop()
    end
    f = f + 1
  end
  turtle.turnRight()
end

function replant()
  turtle.select(15)
  turtle.forward()
  turtle.turnRight()
  turtle.place()
  turtle.turnLeft()
  turtle.forward()
  turtle.turnRight()
  turtle.place()
  turtle.turnLeft()
  turtle.back()
  turtle.place()
  turtle.back()
  turtle.place()
end

while (true) do
  local i = 0
  checkfortree()
  while (i == 0) do
    i = minetree(i)
  end
  dumpitems()
  replant()
end