如何在 tcblisting 中获取图形环境？

Question

考虑一下这个 MWE

\documentclass{article}
\usepackage{graphicx,etoolbox}
\PassOptionsToPackage{final}{listings}
\usepackage[%
   skins
  ,listings
  ,breakable
  ,xparse
  ,documentation
]{tcolorbox}

\NewDocumentCommand\MySmallFigure{o m m m m}{%
\begin{figure}[#2]%
  \parbox[b][][b]{78mm}{#3}%
  \hspace{6mm}%
  \begin{minipage}[b]{\dimexpr\linewidth-78mm-6mm\relax}%
    \caption[#1]{#4}%
    \label{#5}%
  \end{minipage}%
\end{figure}%
}

\AtBeginDocument{%
\newtcblisting[%
  auto counter,
  blend into=listings
]{codetext}[2][]{%
  label = #2,
  listing and text,
  #1,
  }}
\begin{document}

% This works
\MySmallFigure%
[anyone]%
{tb}%
{\includegraphics[width=\linewidth]{example-image-a}}%
{An image ....}%
{example-image-a}

% This doesn’t, since its a figure environment inside a tcolorbox.
\begin{codetext}{figure}
\MySmallFigure%
[anyone]%
{tb}%
{\includegraphics[width=\linewidth]{example-image-a}}%
{An image ....}%
{example-image-a}
\end{codetext}
\end{document}

我想显示该命令的用法，然后显示/\MySmallFigure内该命令的结果。tcolorboxtcblisting

但 ...

./tcbfigure.listing:1: LaTeX 错误：不在外部模式。

...显然，我忽略了一些东西。