Fix argument counting after copying E-type

base/ltcmd.dtx

@@ -1083,11 +1083,15 @@
 \cs_new_eq:NN \@@_copy_grabber_R_alt:w \@@_copy_grabber_D_alt:w
 %    \end{macrocode}
 %
-%   |E| is also straightforward: we just copy the embellishments over:
+%   |E| is straightforward: we just copy the embellishments over, and
+%   increase the current argument number \cs{l_@@_current_arg_int} by
+%   the number of embellishments (minus one because there is a
+%   \cs{int_incr:N} down the line).
 %    \begin{macrocode}
 \cs_new_protected:Npn \@@_copy_grabber_E:w #1 #2 #3 #4
   {
     \tl_put_right:Nn \l_@@_tmpa_tl { {#3} {#4} }
+    \int_add:Nn \l_@@_current_arg_int { \tl_count:n {#4} - 1 }
     \@@_copy_expandable:nnN {#1} {#2}
   }
 \cs_new_eq:NN \@@_copy_grabber_E_long:w \@@_copy_grabber_E:w