print(
    table.concat({{}}, ",") -- invalid value (table) at index 1 in table for 'concat'
)

function __TS__ArrayJoin(self, separator)
	if separator == nil then separator = ", " end

	local result = ""
	for index, value in ipairs(self) do
		if index > 1 then
			result = result + separator
		end
		result = result + tostring(value)
	end
	return result
end

print(
    __TS__ArrayJoin({{}}, ",") -- "table: 0x25"
)