From 77a65423742974039099450e5e0cdf57e9f7ad5d Mon Sep 17 00:00:00 2001
From: Luke Plant <luke@lukeplant.me.uk>
Date: Thu, 28 Dec 2023 20:03:26 +0000
Subject: [PATCH] Fix for crasher in runmailer_pg

---
 CHANGES.rst            | 5 +++++
 src/mailer/postgres.py | 9 ++++++++-
 2 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/CHANGES.rst b/CHANGES.rst
index 259d167..2fc47ff 100644
--- a/CHANGES.rst
+++ b/CHANGES.rst
@@ -1,6 +1,11 @@
 Change log
 ==========
 
+2.3.1 - unreleased
+------------------
+
+* Fixed rare crasher in runmailer_pg when notifications list is empty.
+
 2.3 - 2023-09-25
 ----------------
 
diff --git a/src/mailer/postgres.py b/src/mailer/postgres.py
index 0af2875..983bc57 100644
--- a/src/mailer/postgres.py
+++ b/src/mailer/postgres.py
@@ -60,7 +60,14 @@ def postgres_send_loop():
             pass
         else:
             conn.poll()
-            last = conn.notifies.pop()
+            try:
+                last = conn.notifies.pop()
+            except IndexError:
+                # Not entirely sure how this happens, but it could only happen
+                # if `notifies` is empty, because there are no more notifications
+                # to process.
+                continue
+
             # We don't care about payload or how many NOTIFY there were,
             # we'll just run once, so drop the rest:
             to_drop = conn.notifies