From cf99e405fe22f35900160fc054d401894f101d69 Mon Sep 17 00:00:00 2001
From: Slava Pestov <slava@factorcode.org>
Date: Tue, 5 Feb 2008 18:50:24 -0600
Subject: [PATCH] More intuitive error message for about

---
 extra/help/help.factor | 3 +++
 1 file changed, 3 insertions(+)
 mode change 100644 => 100755 extra/help/help.factor

diff --git a/extra/help/help.factor b/extra/help/help.factor
old mode 100644
new mode 100755
index 87bc0a4b7f..aefbf2aba2
--- a/extra/help/help.factor
+++ b/extra/help/help.factor
@@ -96,6 +96,9 @@ M: word set-article-parent swap "help-parent" set-word-prop ;
     article-content print-content nl ;
 
 : about ( vocab -- )
+    dup vocab [ ] [
+        "No such vocabulary: " swap append throw
+    ] ?if
     dup vocab-help [
         help
     ] [