From fe3de74620abfc0e8d802db024c3680fc68f71d8 Mon Sep 17 00:00:00 2001
From: fang <git@fang.io>
Date: Mon, 30 May 2022 16:08:59 +0200
Subject: [PATCH] clay: render syntax errors at end of file

Previously, if the pointer for a syntax error pointed to the end of the file
(and the file ended in a newline) the code snippet rendering would try to
display a line _beyond_ the end of the file, causing a crash.

Here, we detect that case, and display `<<end of file>>` instead.

(Originally merged through #5812, but got lost somewhere along the way.)

Fixes #6287.
---
 pkg/arvo/sys/vane/clay.hoon | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/pkg/arvo/sys/vane/clay.hoon b/pkg/arvo/sys/vane/clay.hoon
index b9c677a53..bb2c2bd57 100644
--- a/pkg/arvo/sys/vane/clay.hoon
+++ b/pkg/arvo/sys/vane/clay.hoon
@@ -964,8 +964,14 @@
       %-  mean  %-  flop
       =/  lyn  p.hair
       =/  col  q.hair
+      ^-  (list tank)
       :~  leaf+"syntax error at [{<lyn>} {<col>}] in {<pax>}"
-          leaf+(trip (snag (dec lyn) (to-wain:format (crip tex))))
+        ::
+          =/  =wain  (to-wain:format (crip tex))
+          ?:  (gth lyn (lent wain))
+            '<<end of file>>'
+          (snag (dec lyn) wain)
+        ::
           leaf+(runt [(dec col) '-'] "^")
       ==
     ::