1 files changed, 1 insertions, 1 deletions
diff --git a/lib/js/urweb.js b/lib/js/urweb.js
index e211d318..6830945a 100644
--- a/lib/js/urweb.js
+++ b/lib/js/urweb.js
@@ -1575,7 +1575,7 @@ function rv(chn, parse, k) {
         er("May not 'recv' in main thread of 'code' for <active>");
 
     if (chn == null)
-        return;
+        er("Client-side code tried to recv() from a channel belonging to a different page view.");
 
     if (chn < 0)
         whine("Out-of-bounds channel receive");