Test for blank reference fails

[dcpurton]

When passing a blank reference to the scripture environment, the test for a blank reference fails.

MWE

The two boxes should look the same, but they don't.

\documentclass{article}
\usepackage{scripture}
\usepackage{framed}
\begin{document}
\noindent
\begin{minipage}{11cm}
  \begin{framed}
    \begin{scripture}[][]
      \vs{16}For God so loved the world that he gave his one and only Son,
      that whoever believes in him shall not perish but have eternal life.
    \end{scripture}
  \end{framed}

  \begin{framed}
    \begin{scripture}
      \vs{16}For God so loved the world that he gave his one and only Son,
      that whoever believes in him shall not perish but have eternal life.
    \end{scripture}
  \end{framed}
\end{minipage}
\end{document}