From b9781c4903f95a9e12447a3c1be8b754e8865997 Mon Sep 17 00:00:00 2001
From: Shahar Mike <chakaz@users.noreply.github.com>
Date: Sun, 5 Nov 2023 13:31:28 +0200
Subject: [PATCH] fix(test): Don't access null pointer (#2126)

This caused a UBSan warning to be printed in test `DflyEngineTest.Bug207`

```
/usr/include/c++/11/bits/stl_vector.h:1046:34: runtime error: reference binding to null pointer of type 'struct value_type'
```
---
 src/server/db_slice.cc | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/src/server/db_slice.cc b/src/server/db_slice.cc
index 7131ef2b9..39d611083 100644
--- a/src/server/db_slice.cc
+++ b/src/server/db_slice.cc
@@ -1183,9 +1183,12 @@ finish:
   // send the deletion to the replicas.
   // fiber preemption could happen in this phase.
   vector<string_view> args(keys_to_journal.begin(), keys_to_journal.end());
-  ArgSlice delete_args(&args[0], args.size());
-  if (auto journal = owner_->journal(); journal) {
-    journal->RecordEntry(0, journal::Op::EXPIRED, db_ind, 1, make_pair("DEL", delete_args), false);
+  if (!args.empty()) {
+    ArgSlice delete_args(&args[0], args.size());
+    if (auto journal = owner_->journal(); journal) {
+      journal->RecordEntry(0, journal::Op::EXPIRED, db_ind, 1, make_pair("DEL", delete_args),
+                           false);
+    }
   }
 
   auto time_finish = absl::GetCurrentTimeNanos();