How to make script keep running even when it cant find the thing its looking for?

I would rewrite it like this:

for index, child in pairs(player.Character:GetChildren()) do
    if child:IsA("Clothing") or child:IsA("ShirtGraphic") then
        child:Destroy()
    end
end

repeat wait() 

until workspace:FindFirstChild(player.Name) -- waits until the character is a descendant of workspace or loaded

--player.Character:WaitForChild("Shirt") -- THIS WONT WORK IF THE PLAYER DOESN'T HAVE A SHIRT, THE SCRIPT WILL CONTINUE TO WAIT UNTIL A SHIRT INSTANCE IS IN THE CHARACTERS MODEL
    if player.Character:FindFirstChild("Shirt") then
        player.Character.Shirt:Destroy()
    else
    print('No Shirt Detected')
    end

    if player.Character:FindFirstChild("Pants") then
        player.Character.Pants:Destroy()
    else
    print('No Pants Detected')
    end

    if player.Character:FindFirstChild("ShirtGraphic") then
        player.Character.ShirtGraphic:Destroy()
    else
    print('No Shirt Graphic Detected')
    end