I get this error when I attempt to run the code.. attempt to index global 'file' (a nil value) stack traceback:

Question

I get this error when I attempt to run the code.. attempt to index global 'file' (a nil value) stack traceback: I am trying to import a csv file on vrep but its giving me this error.

readFile=function(filename)
     file = io.open(filename, "r")
     matrix = {}
     for row in file:lines() do
        print(row)
        nums = {}
        for num in row:gmatch("%-*%d+%.*%d*") do
            print(num)
            table.insert(nums, tonumber(num))
        end
        table.insert(matrix, nums)
     end
     return matrix
end

has_grabed_an_object = false
grab_object=nil

jh={-1,-1,-1,-1,-1,-1}
for i=1,6,1 do
    jh[i]=sim.getObjectHandle('LBR_iiwa_7_R800_joint'..i)
end
Dummy_target=sim.getObjectHandle('Target')
accel=5
jerk=10
currentVel={0,0,0,0,0,0,0}
currentAccel={0,0,0,0,0,0,0}
maxVel={0.5,0.5,0.5,0.5,0.5,0.5,0.5}
maxAccel={0.5,0.5,0.5,0.5,0.5,0.5,0.5}
maxJerk={0.5,0.5,0.5,0.5,0.5,0.5,0.5}
targetVel={0,0,0,0,0,0,0}

positions = readFile("pickup1.csv")
for index, points in ipairs(positions) do
    sim.rmlMoveToPosition(Dummy_target, -1, -1, currentVel, currentAccel, maxVel, maxAccel, maxJerk, points, targetQuaternion, targetVel)
end