Unexpected error with no-glyph and XeTeX

[jbezos]

With the following minimal example I would expect an error (XeTeX, obviously):

\documentclass{article}
\usepackage{fontspec}
\setmainfont[HyphenChar="1000]{FreeSerif}  % It doesn't exist

But the error is not the expected one:

! Undefined control sequence.
<argument> \__fontspec_error:nxx 
                      {no-glyph}{\l_fontspec_fontname_tl }{"1000}