Broken raycaster in TIC-80

-- title:  Ray-casting test
-- desc:   Simple 3D test
-- script: lua
-- input:  gamepad
screenWidth=240;screenHeight=136
mapWidth=30;mapHeight=17
player={x=0,y=0,angle=0,walkSpeed=1,angleSpeed=0.1}
found=false
for x=0,mapWidth-1 do
    for y=0,mapHeight-1 do
        if(mget(x,y)==5)then
            player.x=x*8
            player.y=y*8
            found=true;break
        end
    end
    if(found)then break end
end
function sget(x,y)
    x=math.floor(x);y=math.floor(y)
    local addr=0x4000+(x//8+y//8*16)*16
    return peek4(addr*2+x%8+y%8*8)
end
function TIC()
    --Player movement
    if btn(2)then player.angle=player.angle-player.angleSpeed end
    if btn(3)then player.angle=player.angle+player.angleSpeed end
    if btn(0)then --Forwards
        player.x=player.x+(math.cos(player.angle)*player.walkSpeed)
        player.y=player.y+(math.sin(player.angle)*player.walkSpeed)
    elseif btn(1)then --Backwards
        player.x=player.x-(math.cos(player.angle)*player.walkSpeed)
        player.y=player.y-(math.sin(player.angle)*player.walkSpeed)
    end
    --Drawing
    cls()
    maxRange=300
    for x=0,screenWidth-1 do
        rayX=player.x+(math.cos(player.angle+(math.pi/2))*5*((x/screenWidth)-.5))
        rayY=player.y+(math.sin(player.angle+(math.pi/2))*5*((x/screenWidth)-.5))
        rayAngle=player.angle+(((x/screenWidth)-.5)*2)
        rayDistance=0
        hit=false
        for i=0,maxRange do
            stepSize=0.1+((i/maxRange)*2)
            rayX=rayX+(math.cos(rayAngle)*stepSize)
            rayY=rayY+(math.sin(rayAngle)*stepSize)
            rayDistance=rayDistance+stepSize
            tile=mget(rayX/8,rayY/8)
            if(tile==2 or tile==3)then
                side=math.floor((((math.atan(((rayY/8)%1)-.5,((rayX/8)%1)-.5)/(math.pi*2))-0.125)%1)*4)
                hit=true
                break
            end
        end
        for y=0,screenHeight-1 do
            wallHeight=((screenHeight/2)/rayDistance)*8
            if(hit and math.abs(y-(screenHeight/2))<wallHeight)then
                if(side==0)then
                    xTexture=rayX
                elseif(side==1)then
                    xTexture=rayY
                elseif(side==2)then
                    xTexture=-rayX
                elseif(side==3)then
                    xTexture=-rayY
                end
                pix(x,y,sget((tile*16)+(xTexture%8),(((y-((screenHeight/2)-wallHeight))/(wallHeight*2))*8)))
            end
        end
    end
end