Hello, I think there is a typo of l3names.dtx.

Index: l3kernel/l3names.dtx
===================================================================
--- l3kernel/l3names.dtx    (revision 3691)
+++ l3kernel/l3names.dtx    (working copy)
@@ -612,7 +612,7 @@
 \tex_let:D \tex_everymath:D         \frozen@everymath
 \tex_let:D \tex_hyphen:D            \@@hyph
 \tex_let:D \tex_input:D             \@@input
-\tex_let:D \tex_italic_correction:D \@@italiccorr
+\tex_let:D \tex_italiccor:D         \@@italiccorr
 \tex_let:D \tex_underline:D         \@@underline
 %    \end{macrocode}
 % That is also true for the \pkg{luatex} package for \LaTeXe{}.

regards