Make plain 'keyword' style pop out in bright red (should never be seen)

preamble.tex

@@ -253,7 +253,7 @@
   keepspaces,                      % don't remove space such as those after closing parenthesis
   captionpos=b,                    % sets the caption-position to bottom
   commentstyle=\color{commentcolor}\sffamily, % comment style
-  keywordstyle=\color{blue}\ttfamily\bfseries,       % keyword style
+  keywordstyle=\color{red},        % Unused keyword style in bright red to make it easy to detect and fix.
   keywordstyle=[1]\color{keywordcolor1},
   keywordstyle=[2]\color{keywordcolor1}\bfseries,
   keywordstyle=[3]\color{keywordcolor3},