Polynom 包双算子

Question

我正在尝试排版多项式长除法问题，但得到了双重运算符。

\documentclass{standalone}
\usepackage{polynom}
%% macro to remove 1 coefficients
\makeatletter
\let\pldx@saved@PrintRational\pld@PrintRational
\renewcommand*{\pld@PrintRational}[2]{%
  \def\pldx@do{\pldx@PrintRational{#1}{#2}}%
  \futurelet\pldx@token\pldx@do
}
\newcommand*{\pldx@PrintRational}[2]{%
  \let\pldx@do\@firstofone
  \ifx\pldx@token\pld@S
    \def\pldx@a{#1}%
    \def\pldx@b{#2}%
    \ifx\pldx@a\pldx@b
      \let\pldx@do\@gobble
    \fi
  \fi
  \pldx@do{%
    \pldx@saved@PrintRational{#1}{#2}%
  }%
}
\makeatother
\begin{document}
    $$\polylongdiv{3x^2 + ax + a + 9}{x + 2}$$
\end{document}

给我这个：

我希望最后一行不要有 +-2。