Rendering of warning yields invalid LaTeX?

[codeZeilen]

Thanks for creating and maintaining knitr! 🌻

During rendering a rather large report, I encountered an issue that boils down to the MWE below. Not sure yet whether this is a knitr or a user problem. 🙂 Happy about any hint to what might be going wrong here.

\documentclass{article}  
\begin{document}
\begin{figure}  
\begin{center}  
<<1, fig.width=11, fig=TRUE, echo=FALSE>>= 
x = cumsum(rnorm(100))
# uncomment to make it work: x + 2
warning("last warning")  
plot(x)
@
\end{center} 
\end{figure} 
\end{document}

This seems to result in invalid LaTeX when processed using:

knit(Sweave2knitr("./full.l"))

When textual output is added by uncommenting x+2. The resulting LaTeX is valid. (Also when disabling output of warnings).

---

The relevant generated LaTeX section that does not compile is:

\begin{document}
\begin{figure}
\begin{center}
\begin{knitrout}
\definecolor{shadecolor}{rgb}{0.969, 0.969, 0.969}\color{fgcolor}\begin{kframe}


{\ttfamily\noindent\color{warningcolor}{\#\# Warning: last warning}}\end{kframe}
\includegraphics[width=\maxwidth]{figure/1-1}
\end{knitrout}
\end{center}
\end{figure}
\end{document}

When added the line x+2 the following LaTeX is generated:

\begin{document}
\begin{figure}
\begin{center}
\begin{knitrout}
\definecolor{shadecolor}{rgb}{0.969, 0.969, 0.969}\color{fgcolor}\begin{kframe}
\begin{verbatim}
... loads of numbers ...
\end{verbatim}


{\ttfamily\noindent\color{warningcolor}{\#\# Warning: last warning}}\end{kframe}
\includegraphics[width=\maxwidth]{figure/1-1} 
\end{knitrout}
\end{center}
\end{figure}
\end{document}

For completeness, the resulting LaTeX error is:

! LaTeX Error: Something's wrong--perhaps a missing \item.
 ...                                                                                                
l.60 ...}{\#\# Warning: last warning}}\end{kframe}