Error "File Not Found"

I’m writing a series of exercises for my students (In Arabic) and Texmaker keeps telling me "File Not Found". What confuses me is that when I compile the code without the body (Only the preamble) it compiles without any errors. However, when I write something in the body it shows me the error. I am using XeLaTeX by the way.
Here is my code that gets compiled:

documentclass[12pt,a4paper]{article}
usepackage[top=0.9cm, bottom = 1.2 cm, right=1 cm, left= 0.8cm]{geometry}
usepackage{amssymb,mathtools,amsthm}
usepackage{fourier}
usepackage{xcolor}
usepackage{multicol}
renewcommand{columnseprule}{1pt}
%renewcommand{columnseprule}{1.5pt}
usepackage{polyglossia}
setdefaultlanguage[calendar=gregorian,numerals=maghrib]{arabic}
newfontfamilyarabicfont[Script=Arabic,Scale=1]{Amiri}
newfontfamilyarabicfontsf[Script=Arabic,Scale=1]{Amiri}

usepackage{romannum}

makeatletter
newcommand*{rom}[1]{expandafter@slowromancapromannumeral #1@}
makeatother
%======================================================
newtheoremstyle{mystyle}
{topsep}% espace avant
{topsep}% espace après
{upshape}% police du corps du théorème
{}% indentation (vide pour rien, parindent)
{bfseriessffamily}% police du titre du théorème
{ :}% ponctuation après le théorème
{newline}% après le titre du théorème (espace ou newline)
{%
 % علق الأسطر 25 و 26 و 28
rule[0.5baselineskip]{0.5textwidth}{1pt}%
newlinefcolorbox{black}{gray!20}{%
thmname{#1}thmnumber{ textup{#2}}thmnote{ textnormal{(#3)}}%
}%
medskip%
}% spécifications du titre

theoremstyle{mystyle}
newtheorem{exo}{تمرين}
%======================================================

title{سلسلة التمارين: المتتاليات العددية}
author{طارق عسيلة}
date{}

begin{document}
begin{center}
bfseriessffamilyLarge سلسلة التمارين: المتتاليات العددية 
large الثالثة ثانوي - شعبة آداب وفلسفة + لغات أجنبية
end{center}
textbf{السنة الدراسية: 2020 - 2021} hfill textbf{من إعداد: طارق عسيلة}
begin{multicols*}{2}

end{multicols*}
end{document} 

Here is my code that does not get compiled:

documentclass[12pt,a4paper]{article}
usepackage[top=0.9cm, bottom = 1.2 cm, right=1 cm, left= 0.8cm]{geometry}
usepackage{amssymb,mathtools,amsthm}
usepackage{fourier}
usepackage{xcolor}
usepackage{multicol}
renewcommand{columnseprule}{1pt}
%renewcommand{columnseprule}{1.5pt}
usepackage{polyglossia}
setdefaultlanguage[calendar=gregorian,numerals=maghrib]{arabic}
newfontfamilyarabicfont[Script=Arabic,Scale=1]{Amiri}
newfontfamilyarabicfontsf[Script=Arabic,Scale=1]{Amiri}

usepackage{romannum}

makeatletter
newcommand*{rom}[1]{expandafter@slowromancapromannumeral #1@}
makeatother
%======================================================
newtheoremstyle{mystyle}
{topsep}% espace avant
{topsep}% espace après
{upshape}% police du corps du théorème
{}% indentation (vide pour rien, parindent)
{bfseriessffamily}% police du titre du théorème
{ :}% ponctuation après le théorème
{newline}% après le titre du théorème (espace ou newline)
{%
 % علق الأسطر 25 و 26 و 28
rule[0.5baselineskip]{0.5textwidth}{1pt}%
newlinefcolorbox{black}{gray!20}{%
thmname{#1}thmnumber{ textup{#2}}thmnote{ textnormal{(#3)}}%
}%
medskip%
}% spécifications du titre

theoremstyle{mystyle}
newtheorem{exo}{تمرين}
%======================================================

title{سلسلة التمارين: المتتاليات العددية}
author{طارق عسيلة}
date{}

begin{document}
begin{center}
bfseriessffamilyLarge سلسلة التمارين: المتتاليات العددية 
large الثالثة ثانوي - شعبة آداب وفلسفة + لغات أجنبية
end{center}
textbf{السنة الدراسية: 2020 - 2021} hfill textbf{من إعداد: طارق عسيلة}
begin{multicols*}{2}
begin{exo}
rom{1} - لتكن ($U_n$) متتابية حيث: ($U_n = 3n +5$). أحسب الحدود $U_0, U_1, U_2$. 
end{exo}
end{multicols*}
end{document} 

usepackage{fourier}