So I am building a game for a game jam over at itch.io, and I'm using this really neat Fantasy Console called TIC-80, found at tic80.com. My issue is that while I understand what the error message is and what it means, I don't understand as to why it's giving me this error.
Error Message (In the TIC-80 console):
>[string "-- title: The Clone
Wars..."]:144: attempt to index a nil
value (field '?')
stack traceback:
[string "-- title: The Clone
Wars..."]:144: in function 'TIC'
The Code in question:
-- title: The Clone Wars
-- author: DinoNuggies
-- desc: Help the jedi destroy the clones!
-- script: lua
--Functions
function sign(n) return n>0 and 1 or n<0 and -1 or 0 end
function lerp(a,b,t) return (1-t)*a t*b end
function tablelength(T)
local count = 0
for _ in pairs(T) do count = count 1 end
return count
end
--End of Functions
--Variables
player = {
spr = 256,
sprMod = 0,
x = 1,
y = 1,
vx = 0,
vy = 0,
dirX = 0,
dirY = 0,
flip = 0,
shoot = false,
}
gun = {
t = 0,
spr = 258,
sprMod = 0,
x = 0,
y = 0,
modX = 0,
modY = 0,
flip = 0,
rot = 0,
}
tile = {
r0 = 0,
r1 = 0,
l0 = 0,
l1 = 0,
u0 = 0,
u1 = 0,
d0 = 0,
d1 = 0,
m = 0,
}
m = {
x = 0,
y = 0,
left = false,
right = false,
middle = false,
}
cam = {
activate = true,
x = 120,
y = 64,
}
--Bullet Class & Functions
bulletMod = 0
bullet = {}
function bullet:new()
local this = {
spr = 260,
x = player.x,
y = player.y,
vx = 0,
vy = 0,
mx = m.x - (player.x cam.x),
my = m.y - (player.y cam.y),
t = 0,
}
return this
end
function bullet:remove()
local this = {
spr = nil,
x = nil,
y = nil,
vx = nil,
vy = nil,
mx = nil,
my = nil,
t = nil,
}
return this
end
--End of Variables
function TIC()
cls()
--Camera
if cam.activate then
cam.x = math.min(120, lerp(cam.x, 120-player.x, 0.05))
cam.y = math.min(64, lerp(cam.y, 64-player.y, 0.05))
ccx = cam.x / 8 (cam.x % 8 == 0 and 1 or 0)
ccy = cam.y / 8 (cam.y % 8 == 0 and 1 or 0)
end
map(15 - ccx, 8 - ccy, 31, 18, (cam.x % 8) - 8, (cam.y % 8) - 8, 0)
--End of Camera
--Gun Physics
m.x, m.y, m.left, m.middle, m.right = mouse()
gun.x = player.x cam.x
gun.y = player.y cam.y
bullets = tablelength(bullet) - 2
flick = (time() // 16) % 16 == 0
if m.left then m.leftp = flick else m.leftp = false end
--Gun Display
if m.x > player.x cam.x 4 then
gun.flip = 0
gun.modX = 4
else
gun.flip = 1
gun.modX = -4
end
--Gun Firing
if m.leftp == true then
bullet[bullets] = bullet:new()
if m.x > player.x cam.x 4 then
bullet[bullets].vx = 8
else
bullet[bullets].vx = -8
end
end
--End of Gun Physics
--Bullet Physics
if bullets > 0 then
for i=0,bullets-1 do
bullet[i].x = bullet[i].x bullet[i].vx --LINE 144, THE ONE IN QUESTION
bullet[i].y = bullet[i].y bullet[i].vy
spr(bullet[i].spr, bullet[i].x cam.x, bullet[i].y cam.y, 0, 1)
bullet[i].t = bullet[i].t 1
if bullet[i].t > 16 then
bullet[i] = bullet:remove()
bullet[i] = nil
end
end
end
bullets = tablelength(bullet) - 2
--End of Bullet Physics
--Drawing
--Sprites
spr(player.spr player.sprMod, player.x cam.x, player.y cam.y, 0, 1, player.flip)
spr(gun.spr gun.sprMod, gun.x gun.modX, gun.y gun.modY, 0, 1, gun.flip, gun.rot)
--Debug
print("Debug:", 1, 1, 11)
print("X: " .. (player.x // 8) 15 .. " Y: " .. (player.y // 8) 9, 1, 8, 11)
print("BLTs: " .. bullets .. " ", 1, 16, 11)
--End of Drawing
--Player Movement
player.x = player.x player.vx
player.y = player.y player.vy
if key(1) and player.x > -120 then
player.vx = -1
player.sprMod = 1
player.dirX = 0
elseif key(4) then
player.vx = 1
player.sprMod = 0
player.dirX = 1
else
player.vx = 0
end
if key(23) and player.y > -64 then
player.vy = -1
player.dirY = 0
elseif key(19) then
player.vy = 1
player.dirY = 1
else
player.vy = 0
end
if btnp(0) then player.y = player.y - 1
elseif btnp(1) then player.y = player.y 1
elseif btnp(2) then player.x = player.x - 1
elseif btnp(3) then player.x = player.x 1
end
--End of Movement
--Player Collision
tile.r0 = mget(((player.x 7) // 8) 15, ((player.y - 9) // 8) 9)
tile.r1 = mget(((player.x 7) // 8) 15, ((player.y - 2) // 8) 9)
tile.l0 = mget(((player.x - 2) // 8) 15, ((player.y - 9) // 8) 9)
tile.l1 = mget(((player.x - 2) // 8) 15, ((player.y - 2) // 8) 9)
tile.u0 = mget(((player.x - 1) // 8) 15, ((player.y - 10) // 8) 9)
tile.u1 = mget(((player.x 6) // 8) 15, ((player.y - 10) // 8) 9)
tile.d0 = mget(((player.x - 1) // 8) 15, ((player.y - 1) // 8) 9)
tile.d1 = mget(((player.x 6) // 8) 15, ((player.y - 1) // 8) 9)
if player.dirX == 1 then
if fget(tile.r0, 0) or fget(tile.r1, 0) then
player.vx = 0
end
elseif player.dirX == 0 then
if fget(tile.l0, 0) or fget(tile.l1, 0) then
player.vx = 0
end
end
if player.dirY == 0 then
if fget(tile.u0, 0) or fget(tile.u1, 0) then
player.vy = 0
end
elseif player.dirY == 1 then
if fget(tile.d0, 0) or fget(tile.d1, 0) then
player.vy = 0
end
end
--End of Player Collision
--Misc
if keyp(3) then
if cam.activate then
cam.activate = false
else
cam.activate = true
end
end
--End of Misc
end
--DON'T WORRY ABOUT ANYTHING PAST THIS POINT, IT'S ONLY SPRITE AND TILE DEFINITIONS FOR TIC-80 VISUALS
-- <TILES>
-- 000:6666666666666666666666666666666666666666666666666666666666666666
-- 001:6666666666566566666666656666666665665666666665666566666666666666
-- 002:6668666666898566666866656666666665665866686689868986686668666666
-- 003:6656556666555556555556555555556555555555665555556556555666655566
-- 016:dddddddeddddddefddeeeeffddeeeeffddeeeeffddeeeeffdeffffffefffffff
-- 017:6226622661266126222222221121112161266126612661265126512665266525
-- 018:6228622661298126222222221121112161266126612681268126512668266525
-- 019:6226522661255126222222221121112151255125612551255126512665255525
-- </TILES>
-- <SPRITES>
-- 000:00cccc000cccccd00cbbbbb0ccbbcbbdcccfefcd0dddddd000ceec0000c00c00
-- 001:00cccc000cccccd00bbbbbd0cbbcbbcdccfefccd0dddddd000ceec0000c00c00
-- 002:000000000000000000000000000eeeed000efff0000ef0000000000000000000
-- 003:0000ed00000eef0000eef0000eef000000eef000000ee0000000000000000000
-- 004:0000000000000000000000000aaaaaa00aaaaaa0000000000000000000000000
-- </SPRITES>
-- <MAP>
-- 000:010101010101010101010101010101010101010101010101010101010101010000000000000000000000101010000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000001
-- 001:010000000000000000000000000000101000101000001000000010101001010000000000100000000000101010000000000000000000100000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000001
-- 002:010001000100010000000000000010000000100010001000100010001001010000000010100000000000101010000000000000001010100000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000001
-- 003:010001000100000000000000000000101000100010001000100010100001010000000010000000000000101000000000000000001000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000001
-- 004:010001010100010000000000000000001000100010001000100010000001010000000010000000000000101010000000000000000000001000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000001
-- 005:010001000100010000000000000010100000001010000010100010000001010000000010000000000000101010000000000000000000101000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000001
-- 006:010000000000000000000000000101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000001
-- 007:010000000000000000000000000101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000001
-- 008:010000000000000000000000000101301010000000000000000000000000000000000000101010000000101000000000000000000010101000000001000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000001
-- 009:010000000000000000000000000101101010100000000000000000000000000000001010101000000000101000000000000000000000000000000001000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000001
-- 010:010000000000000000000000000101101010000000000001111101000000001111111121211111110000101000000000000000000000000000000001000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000001
-- 011:010000000000000000000000000101000000000000001000000001000000000000001020101000000000101000000000000000000000000000000001000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000001
-- 012:010000000000000000000000000101000000000000011111111101010001010000101010000000000010101000000000000000000000000000000001000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000001
-- 013:010000000000000000000000000101000000000010101000000001011101010000101000000000000010100000000000000000000000000000000001000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000001
-- 014:010000000000000000000000000101000000000010101010000000000000010000000000000000000010100000000000000000000000000000000001000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000001
-- 015:010000000000000000000000000101000000000000000000000000000000010000000000000000001010000000000000000000000000000000000001000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000001
-- 016:010101010101010101010101010101000000000000000000000000000000010000000000000000001010000000000000001010000000000000000001000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000001
-- 017:010101010101010101010101010101000000000000000000000000000000000000000000000000101010000000000010102000000000000000000001000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000001
-- 018:000000000000000000000000000101000000000000000000000010100000000000000000000000101000000000001010000000000000000000000001000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
-- 019:000000000000000000001010000101000000000000000000000000100000000000000000000010101000001111211110000000001010000000000001000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
-- 020:000000001000000000001000000101000000000000000000000000101000000000000000001010101000000010101011111100000000000000000001000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
-- 021:000000000000000000001010100101101010000000000000000000000000000000000000101000000000001010200000000011110000000000000001000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
-- 022:000000000000000000000000000101001010100000000000000000000000000000000010101000000010101010100000000000001111000000000001000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
-- 023:000000000000000000000000000101000000000000000000000000000000000000001010100000000010101010000000000000000000110000000001000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
-- 024:000000000000000000000000000101000000000000000000000000000000000000001010100000001020201000000000000000100000001100102001000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
-- 025:000000000000000000000000000101000000000000000000000000000000000000101010000000001020100000000000000000100000000011212101000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
-- 026:000000101000000000000000000101000000000000000000000000000000001010100010000000001010100000000010000000100010100010101001000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
-- 027:000000101010000000000000100101000000000000000010101010101010101010000010000000001010000000000000101010000000001010000001000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
-- 028:000000100010000000000000100101000000000000000000000000001010101000101010000000001010000010101010000000000000000000000001000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
-- 029:000000001010000000000000000101000000000000000000000000000010100000000000000000001010000000000000000000100010000000000001000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
-- 030:000000001010000000000000000101100000000000000000000000000000000000000000000000001000000000001000000000100000000000000001000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
-- 031:000000001010000000000000000101000000000000000000000000000000000000000000000000000000000000000000000000000000000000000001000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
-- 032:000000000000000000000000000101000000000000000000000000000000000000000000000000000000000000000000000000000000000000000001000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
-- 033:000000000000000000000000000101010101010101010101010101010101010101010101010101010101010101010101010101010101010101010101000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
-- 135:010101010101010101010101010101010101010101010101010101010101010000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000001
-- </MAP>
-- <WAVES>
-- 000:00000000ffffffff00000000ffffffff
-- 001:0123456789abcdeffedcba9876543210
-- 002:0123456789abcdef0123456789abcdef
-- </WAVES>
-- <SFX>
-- 000:020002000200020002000200020002000200020002000200020002000200020002000200020002000200020002000200020002000200020002000200304000000000
-- 001:020002000200020002000200020002000200020002000200020002000200020002000200020002000200020002000200020002000200020002000200307000000000
-- 002:02000200020002000200020002000200020002000200020002000200020002000200020002000200020002000200020002000200020002000200020030b000000000
-- </SFX>
-- <FLAGS>
-- 000:00000000000000000000000000000000101010100000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
-- </FLAGS>
-- <PALETTE>
-- 000:1a1c2c5d2810814428ca9581ffcd7575ae442495482571793c55c22c9dfae20000000000f4f4f494b0c2566c86333c57
-- </PALETTE>
What triggers the error, is after the player fires the second bullet. After firing one, the bullet is created, displayed, and despawned on queue, but after the second bullet starts existing, it stops and gives me the error. I've switched things around quite a bit, and it seems like every time I reference to one of the bullet objects values when more then one exists, it sends me the error, which is what I don't understand, as i thought I had already solved that problem with the for loops.
So if you noticed anything right off the bat that doesn't look quite right, let me know, and if you don't know anything about TIC-80 or what the API does, I'm sure the TIC-80 website can explain it way better then me.
If you want to run the game, to see the issue in action and mess around with the code, download TIC-80 from the website and run this file: https://drive.google.com/file/d/18ti0NboNNN9Yog6l_n73usF_eX_86EN4/view?usp=sharing
CodePudding user response：
Let's take a look at your bullet handling
First call to TIC:
bullets is 0. We add one bullet into bullet[0]
Second call:
bullets is 1. We add one bullet into bullet[1].
Now, as bullets > 0 we enter the bullet physics if statement.
We do some calculations to that bullet and increment bullet[0].t
The following calls we do the same. We add a bullet and process all but the new bullet as we did above.
When a bullet's t field becomes > 16 we remove it from bullet.
So first we remove the oldest bullet bullet[0]. But in the following call we again start our loop at i = 0. so bullet[i] is nil and hence indexing it in bullet[i].x causes the observed error.
Side note:
This makes no sense.
function bullet:remove()
local this = {
spr = nil,
x = nil,
y = nil,
vx = nil,
vy = nil,
mx = nil,
my = nil,
t = nil,
}
return this
end
A table with all nil values is just an empty table. So simply return an empty table.
On top of that you don't need that function as it does nothing useful.
bullet[i] = bullet:remove()
bullet[i] = nil
The first line is non necessary. You don't have to assign an emtpy table and then nil. Just assign nil.
If you'd just keep the bullets in the array part of the table you wouldn't need your own tablelength function and then subtract 2 btw. Then you could also use table.remove to remove bullets without creating unexpected gaps in your bullet list.