I'm at a loss why the proper code like this one would produce "undefined control sequence" at every \hline:
\begin{center}\begin{tabular}{ |c|c|c| } \hline cell1 & cell2 & cell3 \\ cell4 & cell5 & cell6 \\ cell7 & cell8 & cell9 \\ \hline\end{tabular}\end{center}Maybe it has something to do with my imports?
\usepackage[preprint]{neurips_2019}\usepackage{arydshln}\usepackage[utf8]{inputenc} % allow utf-8 input\usepackage[T1]{fontenc} % use 8-bit T1 fonts\usepackage{url} % simple URL typesetting\usepackage{booktabs} % professional-quality tables\usepackage{amsfonts} % blackboard math symbols\usepackage{nicefrac} % compact symbols for 1/2, etc.\usepackage{microtype} % microtypography\usepackage{graphicx}\usepackage{subfigure}\usepackage{multirow}\usepackage{natbib}\usepackage{threeparttable}\usepackage{makecell}\usepackage{booktabs} % for professional tables\usepackage{float} %to fix figures\usepackage{amsfonts,amsmath,amssymb,amsthm,mathtools} % various math stuff\usepackage{wrapfig} % Allow wrapping of text around figures\usepackage{mdwlist} % Make list items closer together: itemize*, enumerate*\usepackage{sidecap} % For putting caption beside figure\usepackage{bbm}\usepackage{bm,amsbsy} % for bold symbols% \usepackage{subcaption} % apparently contains errors\usepackage{caption}\usepackage{xcolor}\usepackage{algorithm,algorithmic}\usepackage{hyperref} % hyperlinks
