From 7a59acf2485d21b87f67a7ed7a72d0ea80bc5582 Mon Sep 17 00:00:00 2001
From: Tomasz Grabiec <tgrabiec@scylladb.com>
Date: Thu, 23 Nov 2023 00:29:28 +0100
Subject: [PATCH] tablets: Fail gracefully when migrating tablet has no pending
 replica

Before the patch we SIGSEGV trying to access pending replica in this
case. Fail early instead.
---
 replica/tablets.cc | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/replica/tablets.cc b/replica/tablets.cc
index e2f4c2cbfd..33ba821b7a 100644
--- a/replica/tablets.cc
+++ b/replica/tablets.cc
@@ -213,6 +213,10 @@ future<tablet_metadata> read_tablet_metadata(cql3::query_processor& qp) {
             for (auto&& r : tablet_replicas) {
                 pending.erase(r);
             }
+            if (pending.size() == 0) {
+                throw std::runtime_error(format("Stage set but no pending replica for table {} tablet {}",
+                                                table, current->tid));
+            }
             if (pending.size() > 1) {
                 throw std::runtime_error(format("Too many pending replicas for table {} tablet {}: {}",
                                                 table, current->tid, pending));