strucPDF causes errors with \hline in longtable

[dsavransky]

Describe the bug
longtable environment cannot include \hline when strucPDF is in use.

To Reproduce
MWE:

\documentclass[11pt,article,oneside,tagged]{article}
\usepackage[left=1in,top=1in,right=1in,bottom=1in,footskip = 0.333in]{geometry}
\usepackage[T1]{fontenc}
\usepackage{longtable} %provide longtable
\usepackage[tagged, highstructure]{strucPDF}

\begin{document}
\begin{longtable}{ p{0.1\textwidth} | p{0.8\textwidth}  }
%\hline
1 & 2\\
3 & 4\\
%\hline
\end{longtable}
\end{document}

Expected behavior
Compiles correctly as shown. Uncommenting either \hline command produces the error:

./test.tex:14: A <box> was supposed to be here.
<to be read again> 
                   \toks@ 
l.14 1
       & 2\\
? 

Log messages
If applicable, add log outputs or screenshots to help explain your problem.

Tex Installation (please complete the following information):

• OS: macos 10.14.5
• 'TeX distribution: MacTex (TexLive)
• Version 2019

Additional context
tabularx and tabular all work as expected.

Thank you.