patch 8.2.3961: error messages are spread out

Problem:    Error messages are spread out.
Solution:   Move more errors to errors.h.
diff --git a/src/map.c b/src/map.c
index 311f4da..94d2bdf 100644
--- a/src/map.c
+++ b/src/map.c
@@ -916,7 +916,7 @@
     local = (STRCMP(arg, "<buffer>") == 0);
     if (!local && *arg != NUL)
     {
-	emsg(_(e_invarg));
+	emsg(_(e_invalid_argument));
 	return;
     }
 
@@ -2753,7 +2753,7 @@
     switch (do_map((*cmdp == 'n') ? 2 : (*cmdp == 'u'),
 						    eap->arg, mode, isabbrev))
     {
-	case 1: emsg(_(e_invarg));
+	case 1: emsg(_(e_invalid_argument));
 		break;
 	case 2: emsg((isabbrev ? _(e_no_such_abbreviation)
 						      : _(e_no_such_mapping)));