Create a new error for when a char is needed but event-to-character gives nil lisp/ChangeLog addition: 2015-03-14 Aidan Kehoe <kehoea@parhasard.net> * cmdloop.el (no-character-typed): New error, for those cases when a keystroke is to be treated as a character but has no character equivalent. * cmdloop.el (read-char-1): Use it. * keymap.el (synthesize-keysym): Use it. src/ChangeLog addition: 2015-03-14 Aidan Kehoe <kehoea@parhasard.net> * general-slots.h (Qno_character_typed): New error symbol. * event-stream.c (syms_of_event_stream): Define it. New error, for those cases when a keystroke is to be treated as a character in some context but has no character equivalent. * cmds.c (Fself_insert_command): Use it.

--- a/src/event-stream.c	Sat Mar 14 01:16:45 2015 +0000
+++ b/src/event-stream.c	Sat Mar 14 01:40:49 2015 +0000
@@ -4920,6 +4920,7 @@
   DEFSYMBOL (Qcommand_event_p);
 
   DEFERROR_STANDARD (Qundefined_keystroke_sequence, Qsyntax_error);
+  DEFERROR_STANDARD (Qno_character_typed, Qundefined_keystroke_sequence);
   DEFERROR_STANDARD (Qinvalid_key_binding, Qinvalid_state);
 
   DEFSUBR (Frecent_keys);