From 1d961838cff168a101069d08a8ab6594f49f0911 Mon Sep 17 00:00:00 2001
From: Cliff Click <cliffc@acm.org>
Date: Tue, 22 Sep 2026 09:32:07 -0700
Subject: Graph viewer on ch4 and25

---
 graph/web/viewer.js | 5 +++++
 1 file changed, 5 insertions(+)

(limited to 'graph/web/viewer.js')

diff --git a/graph/web/viewer.js b/graph/web/viewer.js
index 9aaaa154..ed14651f 100644
--- a/graph/web/viewer.js
+++ b/graph/web/viewer.js
@@ -148,6 +148,11 @@ try {
       try {
         if (message.startsWith("{")) {
           frame = JSON.parse(message);
+          if (frame.error) {
+            failure = "Compile error: " + frame.error;
+            updateUI();
+            return;
+          }
           if (frame.snap.ver !== 1) throw new Error("Unsupported graph version: " + frame.snap.ver);
         } else {
           // Earlier chapters still send bare DOT.
-- 
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