"!pdfTeX error: pdflatex.exe (file tcst1000): Font tcst1000 at 1200 not found" in MikTeX2.9

I am using MikTeX 2.9 (up-to-date) with TeXStudio. A file that compiled correctly in March 2019 now fails with the following error message:

!pdfTeX error: pdflatex.exe (file tcst1000): Font tcst1000 at 1200 not found
 ==> Fatal error occurred, no output PDF file produced!

Here is the MWE (from SWeave you can tell that it was produced by R):

\documentclass{article}

\RequirePackage{amsmath}
\RequirePackage{booktabs}
\usepackage{Sweave}
%\usepackage{lmodern}

\begin{document}

In this paper, I  estimate loss in mean-variance efficiency due to estimation error by running simulations along the lines described in {[email protected]}.

\begin{Schunk}
\begin{Sinput}
> #Load the needed libraries.
> #I use H. Seltman's \texttt{cor2cov} function to get the covariance
> library(MASS)
> library(rJava)
> library(xlsxjars)
> library(xlsx)
\end{Sinput}
\end{Schunk}

\end{document}

If I remove the apostrophe after Seltman, the file compiles without error. The error persists even if I uncomment the \usepackage{lmodern} line.

Thank you.

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