Optimization of solution for full page landscape figures

Comments from various threads have been aggregated and considered resulting in the following implementation.

documentclass{article}%
usepackage{afterpage}%
usepackage{pdflscape}%
usepackage{varioref}%
usepackage{graphicx}%
usepackage{capt-of}%

%
newcommandfloatsummary{}%
newcommandfloatdescription{}%

begin{document}

section{Introduction}

An introduction...

section{Results}

Results are shown in Figure vref{fig:example}


%
afterpage{%
begin{landscape}%
pagestyle{empty}
parbox[c][textwidth][s]{linewidth}{%
%
renewcommandfloatsummary{Short float summary which will appear in toc}%
renewcommandfloatdescription{Longer float description}%
%
vfill%
setlength{fboxrule}{0pt}%
begin{center}%
fbox{%
centering%
includegraphics[width=dimexprlinewidth-2fboxsep-2fboxrulerelax]{example-image.jpg}%
}%
end{center}%
captionof{figure}[floatsummary]{floatsummary.  floatdescription}%
vfill%
}%
label{fig:example}%
end{landscape}%
}%

end{document}

Key, desireable features are:

1. balanced positioning
2. maximizing use of page
3. rotating landscape pages in .pdf
4. avoid blank pages before or after figure
5. avoid blank pages when two or more consecutive landscape figures
   displayed

The inset mwe does result in a .pdf when one pushes compilation through a couple of errors. The question is, what causes the ! LaTeX Error: Something's wrong--perhaps a missing item. and how can the mwe be optimized / improved?

documentclass{article}%
usepackage{afterpage}%
usepackage{pdflscape}%
usepackage{varioref}%
usepackage{graphicx}%
usepackage{capt-of}%

begin{document}

section{Introduction}

An introduction...

section{Results}

Results are shown in Figure vref{fig:example}
%
afterpage{%
begin{landscape}%
pagestyle{empty}
parbox[c][textwidth][c]{linewidth}{%
%
deffloatsummary{Short float summary which will appear in toc}% local to environment
deffloatdescription{Longer float description}%
%
centering
includegraphics[width=linewidth]{example-image.jpg}
captionof{figure}[floatsummary]{floatsummary.  floatdescription}
label{fig:example}% @currentlabel etc. is local to parbox
}% end of parbox
end{landscape}%
}%

end{document}