Compilation Warning - "Negative Labelwidth. This does not make much(enumitem) sense,"

Question

I get a compilation error in the below document. I've made a outline template I like using for my notes, but get a compilation warning with some 'suggestions.' What do these mean? I also get a fancyhdr warning.

\documentclass[11pt,oneside,a4paper]{article}
\usepackage[margin=1in]{geometry}
\usepackage{tikz-cd}
\usepackage{enumitem}
\usepackage{fancyhdr}
\fancyhf{} % sets both header and footer to nothing
\renewcommand{\headrulewidth}{0pt}
\usepackage{fourier-orns}
\pagestyle{fancy}
\fancyhead[L,C]{}
\newcommand\descitem[1]{\item{\bfseries #1}\\}
\renewcommand\headrule{%
\hrulefill
\raisebox{-2.1pt}
{\quad\decofourleft\decotwo\decofourright\quad}%
\hrulefill}
\usepackage{amsfonts}
\usepackage[most]{tcolorbox}
\usepackage{lmodern}
\usepackage{blindtext}
\usepackage{calc}
\usepackage{ragged2e}
\usepackage{mathtools}

\newtcolorbox{notebook}{
text width=4cm,
boxrule=6mm,
enhanced jigsaw, 
enhanced, 
breakable, 
text width=\widthofmytcb,
toprule=0pt,
bottomrule=0pt,
leftrule=0pt,
rightrule=0pt,
width=\linewidth,
halign=justify,
colframe=green!65!black,
colback=green!10,
  boxrule=1pt,
drop shadow=gray,%
}

\usepackage{lineno}
\usepackage{amssymb}



\begin{document}
\begin{center}
\LARGE{Discrete Math}
\end{center}


\begin{enumerate}[wide, labelwidth=!,labelindent=0pt, leftmargin=0em, label=\arabic*, itemsep=1.2cm, parsep=0pt, font=\large\color{red}]
\item[{\huge{$1$}}]{\LARGE{\underline{Questions}}}
\begin{enumerate}
\item (Converse, Inverse, Contrapositive) are there any others? Would you call these operators? Is this similar to typecasting in programming? 
\item Do these apply to quantified statements in the same way they apply to conditional statements? 
\item \[
\begin{drcases}
\text{``if p then q''}\\
\text{``p and not q''}
\end{drcases}
\text{$\,$ are these logically equivalent?}
\]
\item p but q $\equiv$ p and q
\item Why is a biconditional statement different than $\land$
\item Quantified statements are made up of two items
\subitem Predicates $\rightarrow$ make up the domain
\subitem Quantifiers $\rightarrow$ identify items in the domain
\item (p $\rightarrow$ q) $\land$ ($\therefore (\sim$ p)) $\leftarrow$ can I use this notation? 
\item An argument is valid if and only if the premises is true and the conclusion is true? 
\item An argument is invalid if and only if the premises is false and the conclusion is true? 
\item Review Question \# 9 w/ Dr. Walls 2.3
\item What are the Inverse and Converse errors mentioned in the homework? 
\item 
\end{enumerate}
\end{enumerate}
\end{document}

Answer 1

The relationship \leftmargin + \itemindent = \labelindent + \labelwidth + \labelsep must be satisfied. With \leftmargin=0pt and a positive \labelsep, this leaves a negative value for \labelwidth.

You can solve it by using itemindent=!.

\begin{enumerate}[wide, labelwidth=!,itemindent=!,labelindent=0pt, leftmargin=0em, label=\arabic*, itemsep=1.2cm, parsep=0pt, font=\large\color{red}]

(And, by the way, you should increase \headheight)