patch 8.2.4008: error messages are spread out

Problem:    Error messages are spread out.
Solution:   Move more error messages to errors.h.
diff --git a/src/typval.c b/src/typval.c
index 2ffc4ab..564cc50 100644
--- a/src/typval.c
+++ b/src/typval.c
@@ -209,7 +209,7 @@
 					    STR2NR_ALL, &n, NULL, 0, FALSE);
 	    return n;
 	case VAR_LIST:
-	    emsg(_("E745: Using a List as a Number"));
+	    emsg(_(e_using_list_as_number));
 	    break;
 	case VAR_DICT:
 	    emsg(_(e_using_dictionary_as_number));