lua conky

str = string.format( "%s %d", tset.text, value ) .. "°C"

conky: llua_do_call: function conky_main execution failed: ~/.config/hybrid/lua/hybrid-rings.lua:608: bad argument #3 to 'format' (number expected, got nil)

local function setup_other_text(cr, pt, tset, value)
        local str = ''

        if pt.name == 'platform' then
            str = string.format( "%s %d", tset.text, value ) .. "°C"
        elseif pt.name == 'time' then
            str = string.format( "%02d", value )
        else
            str = string.format( "%s %d", tset.text, value ) .. "%"
        end

        cairo_move_to (cr, tset.x, tset.y)
        cairo_show_text (cr, str)
    end