summary: adding a safe-summary that catches any errors calling summary.

basis/summary/summary.factor

@@ -1,7 +1,7 @@
 ! Copyright (C) 2008 Slava Pestov.
 ! See http://factorcode.org/license.txt for BSD license.
-USING: accessors classes sequences kernel namespaces
-make words math math.parser assocs ;
+USING: accessors assocs classes continuations kernel make math
+math.parser sequences ;
 IN: summary
 
 GENERIC: summary ( object -- string )
@@ -31,3 +31,8 @@ M: assoc summary
 M: f summary object-summary ;
 
 M: integer summary object-summary ;
+
+: safe-summary ( object -- string )
+    [ summary ]
+    [ drop object-summary "~summary error: " "~" surround ]
+    recover ;