Argument \OT1\' has an extra }

Question

This question is a secondary error I receive in TexMaker after running LaTex command to ensure I can run biber as well - link to the related question

! Argument of \OT1\' has an extra }.
<inserted text>
\par
l.118 \printbibliography[title=References]
I've run across a "`}' that doesn't seem to match anything.
For example, `\def\a#1{...}' and `\a}' would produce
this error. If you simply proceed now, the `\par' that
I've just inserted will cause me to report a runaway
argument that might be the root of the problem. But if
your `}' was spurious, just type `2' and it will go away.
Runaway argument?
! Paragraph ended before \OT1\' was complete.
<to be read again>
\par
l.118 \printbibliography[title=References]
I suspect you've forgotten a `}', causing me to apply this
control sequence to too much text. How can we recover?
My plan is to forget the whole thing and hope for the best.

I am quite uncertain how exactly to fix this. Is the problem to do with the } in the .bib file which is being printed?

MWE from the link I posted earlier under a related question which may produce a related error (hyperlinked at the top):

\documentclass[a4paper, 12pt, twoside]{report}

    \usepackage[top=1in, bottom=1in, left=1in, right=1in, paperwidth=8.5in, paperheight=11in]{geometry}
    \usepackage{titlesec}
    \usepackage[utf8]{inputenc}
    \usepackage{etoolbox}
    \titleformat{\chapter}[display]
        {\normalfont\huge\bfseries}{\chaptertitlename\ \thechapter}{20pt}{\Huge}
    \titlespacing*{\chapter}{0pt}{0pt}{20pt}
    \usepackage{xcolor}
    \usepackage{siunitx}
    \usepackage[polish, english]{babel}
    \usepackage{enumitem} % listing package
    \DeclareUnicodeCharacter{0394}{\ensuremath{\Delta}}


    %Referencing Style
    \usepackage{hyperref}
    \hypersetup{colorlinks = true, citecolor = blue} % recolors hyperlinks

    \usepackage
    [backend=biber,
    style=authoryear-comp,
    citestyle=authoryear-icomp,
    maxcitenames=2, % sets limit for et al in citations
    maxbibnames=99, % frees up limits to authors listed in references
    giveninits=true, % initialise each author
    sorting=nyt, % sort by name, author and publication title
    sortcites=false,
    hyperref=true]{biblatex} % citation hyperlinks

    \defbibenvironment{bibliography}
    {\enumerate{}
        {\setlength{\leftmargin}{\bibhang}%
        \setlength{\itemindent}{-\leftmargin}%
        \setlength{\itemsep}{\bibitemsep}%
        \setlength{\parsep}{\bibparsep}}}
    {\endenumerate}
    {\item}

    %Corrections to referencing style

    \DeclareFieldFormat*{title}{{#1}} % * clears formatting of publication titles
    \DeclareFieldFormat*{journaltitle}{\mkbibemph{#1}\isdot} % italicised journal titles
    \DeclareFieldFormat*[inbook]{volume}{\mkbibbold{#1}\isdot} % italicised journal titles

    \renewbibmacro{volume+number+eid}{%
        \setunit{\adddot\addspace}%
             \printfield{volume}%
             \printfield{number}%
         \setunit{\addcomma\space}%
             \printfield{eid}} % changed volume-number-pages layout

      \renewcommand*{\bibpagespunct}{\ifentrytype{article}{\addcolon}{\addcomma\space}}% colon between volume numbers and pages
    \DeclareFieldFormat[article]{number}{\mkbibparens{#1}} % parentheses around volume number

       \DeclareDelimFormat{translatortypedelim}{\addspace} % parentheses bracket around Ed.

    \DeclareNameAlias{sortname}{family-given} % puts given names after surname
    \DeclareFieldFormat{postnote}{#1}% no postnote prefix in "normal" citation commands
    \DeclareFieldFormat{multipostnote}{#1}% no postnote prefix in "multicite" commands
    \DeclareFieldFormat[article]{pages}{#1}% no prefix for the `pages` field in the articles within bibliography
    \DeclareFieldFormat[article]{volume}{\mkbibbold{#1}}%emboldens volume #
    \renewbibmacro{in:}{}

    \newcommand{\biband}{\ifcurrentname{labelname}{\bibstring{and}}{\&}} % changes citation 'and' to ampersand
    \renewcommand*\finalnamedelim{ \& } % references delimiter becomes ampersand
    \renewcommand*{\nameyeardelim}{\addcomma\space} % adds comma between cited author and year
    \renewcommand*{\compcitedelim}{\addsemicolon\space} % semicolons instead of commas between same author citations


\addbibresource{Bib/References.bib}

    %Paragraph indentation
    \setlength{\parindent}{2em}
    \setlength{\parskip}{0.5em}

\begin{document}

\nocite{*}
    \hypersetup{urlcolor = blue}
\printbibliography[title=References]

\end{document}

Answer 1

I have now solved this and located the bug. It was indeed as @David Carlisle suggested - the issue was with the one spurious \'{i} among a list of bibliography entries containing í's that was causing the problem. It turns out that JabRef .bib handler does not ever convert these automatically, but there is a cleanup setting to do this manually.

Thanks @moewe and @David Carlisle!