Sstrhsrtj

The following example gives me an error

documentclass[12pt,oneside]{report}

usepackage[utf8]{inputenc}

usepackage[T1]{fontenc}

usepackage[french]{babel}

usepackage[a4paper,

            inner=10mm,

            outer=60mm,

            top=20mm,

            bottom=25mm,

            marginparsep=10mm,

            marginparwidth=40mm]{geometry}



usepackage{tikz}

usepackage{tikz-cd}



begin{document}



foo

marginpar{

begin{tikzcd}

    E 

        arrow[bend right=50]{rr}[,label=below:scriptsize $gcirc f$]{}

        arrow[r]{}[,label=above:scriptsize $f$]{}

    & F

        arrow[r]{}[,label=above:scriptsize $g$]{}

    & G

end{tikzcd}

}

bar



end{document}

while the commutative diagramm is compiling correctly when it's not in the margin.

Error is :

! Undefined control sequence.
pgf@matrix@last@nextcell@options ! Package pgf Error: Single
ampersand used with wrong catcode.

This is a wellknown issue, when it is dealing with & used inside an argument, things go wrong (presumably catcodes). Solution use this:

marginpar{

begin{tikzcd}[ampersand replacement=&]

    E 

        arrow[bend right=50]{rr}[,label=below:scriptsize $gcirc f$]{}

        arrow[r]{}[,label=above:scriptsize $f$]{}

    & F

        arrow[r]{}[,label=above:scriptsize $g$]{}

    & G

end{tikzcd}

}