longtabu Missing } inserted error

I’m getting this error:

(./template/changelog.tex
./template/changelog.tex:36: Missing } inserted.
<inserted text> 
                }
l.36 end{longtabu}

while I compile a multifile project.

changelog.tex:

newcommand*mytablecontents{}
foreach x [count=nj] in modifiche
{
    foreach y [count=ni] in x
    {
        ifnumni=5
            xapptomytablecontents{y}
            gapptomytablecontents{}
            gapptomytablecontents{hline}
        else
            xapptomytablecontents{y&}
        fi
    }
}

section*{Diario delle modifiche}

% Impostazioni della tabella
tabulinesep = 2mm % padding
taburowcolors 2{pari .. dispari} % colori delle righe

begin{longtabu}{|X[-1,c]|X[-1,c]|X[1,c]|X[0.6,c]|X[1.3]|} % larghezza delle colonne
hline

rowcolor{header} % colore dell'header

% header
textbf{Versione} & textbf{Data} & textbf{Nominativo}             & textbf{Ruolo}         & multicolumn{1}{c|}{textbf{Descrizione}}
hline

endfirsthead
endhead

mytablecontents

end{longtabu}

I don’t understand where } is missing.