I have a problem with a source.tex and I can't figure it out.
Header is checked beforehand with two questions and gives no problem.
Version 1.4.0 - Ubuntu 18.04 LTS
I have added 64 questions in various groups and they are all like this:

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\element{6.1.2 Necessitem energia}{
\begin{question}{NecessitemEnergia1}
En les darrers décades el consum d'energia arreu del món...
\begin{choiceshoriz}
\correctchoice{ha augmentat molt}
\wrongchoice{ha disminuit una mica}
\wrongchoice{ha augmentat una mica}
\wrongchoice{ha disminuit molt}
\end{choiceshoriz}
\end{question}}
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At the end I choose the questions of the test with these lines:

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@%% Aqui es trien [N] preguntes de cada {grup} i s'afegeixen

\cleargroup{all}
\copygroup¹{6.1.2 Necessitem energia}{all}
\copygroup²{6.1.3 Classificació de fonts d’energia}{all}
\copygroup¹{6.2.1 Central elèctrica}{all}
\copygroup²{6.2.2 Centrals hidroelèctriques}{all}

% Afegim una pàgina en blanc si cal fins a tenir dues pagines:
\AMCaddpagesto{2}

%% Fi de onecopy
}

\end{document}@
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And it always gives me this meassage that I don't know what it means.
Can you please help me to undertand what they mean I how to solve it?:

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@! Missing \endcsname inserted.
<to be read again
\begingroup
l.872 }

! Missing number, treated as zero.
<to be read again
\u8-226-€™
l.872

(Only first errors written)@
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