expl3 errors when check-declarations is used
When using check-declarations one gets a number of errors with media9 /pdfbase.
\RequirePackage[enable-debug,check-declarations]{expl3}
\documentclass{article}
\usepackage{media9}
\begin{document}
abc
\end{document}
! LaTeX3 Error: The variable \g_mix_date_tl has not been declared on line 54.