声明 itemize 时出错（不能在 \the 后使用“\relax”）。

Question

我在声明时收到以下错误逐项列举环境：

错误 main.tex:188 — 不能在 \the 之后使用“\relax”。

错误 main.tex:188 — 未定义控制序列。

错误 main.tex:188 — 缺少数字，视为零。

主文本

\documentclass[a4paper, 11pt, landscape]{article}
\usepackage[utf8]{inputenc}
\usepackage{mathptmx} % more compact font
\usepackage{amsmath,amssymb,amsthm,amsfonts}
\usepackage{mathtools}
\usepackage{multicol}
\usepackage{enumitem}
\usepackage{paralist} % for compacter lists
\usepackage{hyperref} % for Todo's and similar things
\usepackage[left=4.5mm, right=4.5mm, top=4.5mm, bottom=6mm, landscape, nohead, nofoot]{geometry}
\usepackage[small,compact]{titlesec}
\usepackage[usenames,dvipsnames,svgnames,table]{xcolor}
\usepackage{xparse}
\usepackage{tcolorbox}
\newtcolorbox{mybox}[1]{colback=red!5!white,colframe=red!75!black,fonttitle=\bfseries,title=#1,before skip=5pt,after skip=5pt}
\newtcolorbox{criterio}[1]{colback=blue!5!white,colframe=blue!75!black,fonttitle=\bfseries,title=#1}

% compact text
\linespread{0.9}
\setlength{\parindent}{0pt}

% compact lists even more
\setdefaultleftmargin{0em}{0em}{0em}{0em}{0em}{0em}

% compact sections
\titlespacing*{\section}{0pt}{0em}{0em}
\titlespacing*{\subsection}{0pt}{0em}{0em}
\titlespacing*{\subsubsection}{0pt}{0em}{0em}

% coloured section headings for easier read
\titleformat{name=\section}[block]
  {\sffamily}
  {}
  {0pt}
  {\colorsection}
\newcommand{\colorsection}[1]{%
    \colorbox{red!10}{\parbox[t][0em]{\dimexpr\columnwidth-2\fboxsep}{\thesection\ #1}}}


\titleformat{name=\subsection}[block]
  {\sffamily}
  {}
  {0pt}
  {\subcolorsection}
\newcommand{\subcolorsection}[1]{%
    \colorbox{orange!10}{\parbox[t][0em]{\dimexpr\columnwidth-2\fboxsep}{\thesubsection\ #1}}}


\titleformat{name=\subsubsection}[block]
  {\sffamily}
  {}
  {0pt}
  {\subsubcolorsection}
\newcommand{\subsubcolorsection}[1]{%
    \colorbox{blue!10}{\parbox[t][0em]{\dimexpr\columnwidth-2\fboxsep}{\thesubsubsection\ #1}}}
    
% environment for multicols inside a list
\NewDocumentEnvironment{listcols}{O{2} O{0pt}}
    {%
        \bgroup %
        \setlength{\multicolsep}{#2} %
        \begin{multicols*}{#1} %
    }
    {%
        \end{multicols*} %
        \egroup %
    }

% multicols lines & spacing
\setlength{\columnsep}{0.2cm}
\setlength{\columnseprule}{0.2pt}

% No page numbers
\pagenumbering{gobble}

% math helpers
\DeclareMathOperator*{\argmin}{arg\,min}
\DeclareMathOperator*{\argmax}{arg\,max}

\begin{document}
\begin{multicols*}{3}

...

    \begin{criterio}{CR. \emph{del confronto}}
        $\sum_{n=0}^{+\infty}a_n, \sum_{n=0}^{+\infty}b_n, 0\leq a_n \leq b_n$.
        \begin{itemize}
             \item $\sum b_n$ converge $\rightarrow \sum a_n$ converge;  
             \item $\sum a_n$ diverge $\rightarrow \sum b_n$ diverge.
188.    \end{itemize}
    \end{criterio}
        

...


\raggedcolumns
\end{multicols*}
\end{document}