patch 9.1.1223: wrong translation used for encoding failures

Problem:  wrong translation for encoding failures because of using
          literal "from" and "to" in the resulting error message
          (RestorerZ)
Solution: use separate error messages for errors "from" and "to"
          encoding errors.

fixes: #16898
closes: #16918

Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/src/errors.h b/src/errors.h
index a116505..ca5ec85 100644
--- a/src/errors.h
+++ b/src/errors.h
@@ -3660,5 +3660,7 @@
 	INIT(= N_("E1513: Cannot switch buffer. 'winfixbuf' is enabled"));
 EXTERN char e_invalid_return_type_from_findfunc[]
 	INIT(= N_("E1514: 'findfunc' did not return a List type"));
-EXTERN char e_str_encoding_failed[]
-	INIT(= N_("E1515: Unable to convert %s '%s' encoding"));
+EXTERN char e_str_encoding_from_failed[]
+	INIT(= N_("E1515: Unable to convert from '%s' encoding"));
+EXTERN char e_str_encoding_to_failed[]
+	INIT(= N_("E1516: Unable to convert to '%s' encoding"));