better-assert.lua

if not pcall(assert, false, {}) then
    local a = _G.assert
    assert = function(t, m)
        if t == nil then
            error("value expected", 2)
        end
        if not t then
            if m == nil then
                error("assertion failed", 2)
            else
                error(m, 2)
            end
        end
        return t
    end
end