Missing \item when compiling my resume

The class you're using is not very well written.

Change line 117 as shown below:

117   \end{list}\par
118   \vspace{0.5em} % Some space after the list of bullet points

(line 118 is added for clarity; don't add the line numbers, of course).

The missing \par is the problem.

In addition to egreg's comment the example document demonstrates that the rSubsection environment is a list the intended usage is

\begin{rSubsection}{ACME, Inc}{October 2010 - Present}{Web Developer}{Palo Alto, CA}
\item Lorem ipsum dolor sit amet, consectetur adipiscing elit. Donec a diam lectus.
\item Donec et mollis dolor. Praesent et diam eget libero Adobe Coldfusion egestas mattis sit amet vitae augue.
\item Nam tincidunt congue enim, ut porta lorem Microsoft SQL lacinia consectetur.
\item Donec ut libero sed arcu vehicula ultricies a non tortor. Lorem ipsum dolor sit amet, consectetur adipiscing elit.
\item Pellentesque auctor nisi id magna consequat JavaScript sagittis.
\item Aliquam at massa ipsum. Quisque bash bibendum purus convallis nulla ultrices ultricies.
\end{rSubsection}

Your example is a list with no \item and so (for once) the missing item error is related to a missing \item.