Keep getting error: "TakeDamage is not a valid member of Folder" line 22? [closed]

(Keep in mind this was a NPC I found in toolbox) I keep getting the error "TakeDamage is not a valid member of Folder" from line 22. The folder it's referring to is located in the NPC's model, however there are no parts within this folder and none of the code refers to the folder. This error usually happens when the NPC's fighting another NPC. After the error, the script breaks and doesn't damage the enemy like intended.

TL;DR: I have a script that detects when the sword hits another NPC. However, when the NPC is fighting an enemy, the script stops working and returns with the above error.

Below is the code:

local damage = 10

sword = script.Parent.Handle

debounce = false





function swordTouched(hit)
    if (hit.Parent == nil) then return end
    if debounce == false then debounce = true
    local humanoid = hit.Parent:findFirstChild("Blue")  --Looks for Humanoid in attacked NPC
    local vCharacter = Tool.Parent --Character as in the attacked NPC
    local hum = vCharacter:findFirstChild("Red") --Looks for Humanoid in ATTACKING NPC
    if humanoid~=nil and humanoid ~= hum and hum ~= nil then
        local right_arm = vCharacter:FindFirstChild("Right Arm") 
        if (right_arm ~= nil) then
            local joint = right_arm:FindFirstChild("RightGrip")
            if (joint ~= nil and (joint.Part0 == sword or joint.Part1 == sword)) then
                humanoid:TakeDamage(10)
                local randomNoise = math.random(1,2)--Just a sound randomizer
                if randomNoise == 1 then
                script.Parent.Parent.Head.s1:Play()
                else script.Parent.Parent.Head.s2:Play() 
                end
                wait(1) --allows for the sword to be used again by NPC
            end
        end
    end
    debounce = false
    end
end