storepool can panic if relocation happens before gossip update.

[aliher1911]

When restarting node in an active cluster sometime it fails with:

I230206 14:50:58.896856 200 kv/kvserver/store_remove_replica.go:150 ⋮ [T1,n5,s5,r110/1:‹/Table/108/1/"{seatt…-washi…}›,raft] 394  removing replica r110/1
E230206 14:50:58.897133 218 1@util/log/logcrash/crash_reporting.go:188 ⋮ [T1,n5,s5,store-rebalancer] 395  a panic has occurred!
E230206 14:50:58.897133 218 1@util/log/logcrash/crash_reporting.go:188 ⋮ [T1,n5,s5,store-rebalancer] 395 +runtime error: invalid memory address or nil pointer dereference
E230206 14:50:58.897133 218 1@util/log/logcrash/crash_reporting.go:188 ⋮ [T1,n5,s5,store-rebalancer] 395 +(1) attached stack trace
E230206 14:50:58.897133 218 1@util/log/logcrash/crash_reporting.go:188 ⋮ [T1,n5,s5,store-rebalancer] 395 +  -- stack trace:
E230206 14:50:58.897133 218 1@util/log/logcrash/crash_reporting.go:188 ⋮ [T1,n5,s5,store-rebalancer] 395 +  | runtime.gopanic
E230206 14:50:58.897133 218 1@util/log/logcrash/crash_reporting.go:188 ⋮ [T1,n5,s5,store-rebalancer] 395 +  |   GOROOT/src/runtime/panic.go:884
E230206 14:50:58.897133 218 1@util/log/logcrash/crash_reporting.go:188 ⋮ [T1,n5,s5,store-rebalancer] 395 +  | runtime.panicmem
E230206 14:50:58.897133 218 1@util/log/logcrash/crash_reporting.go:188 ⋮ [T1,n5,s5,store-rebalancer] 395 +  |   GOROOT/src/runtime/panic.go:260
E230206 14:50:58.897133 218 1@util/log/logcrash/crash_reporting.go:188 ⋮ [T1,n5,s5,store-rebalancer] 395 +  | runtime.sigpanic
E230206 14:50:58.897133 218 1@util/log/logcrash/crash_reporting.go:188 ⋮ [T1,n5,s5,store-rebalancer] 395 +  |   GOROOT/src/runtime/signal_unix.go:835
E230206 14:50:58.897133 218 1@util/log/logcrash/crash_reporting.go:188 ⋮ [T1,n5,s5,store-rebalancer] 395 +  | github.com/cockroachdb/cockroach/pkg/kv/kvserver/allocator/storepool.(*StorePool).UpdateLocalStoreAfterRelocate.func1
E230206 14:50:58.897133 218 1@util/log/logcrash/crash_reporting.go:188 ⋮ [T1,n5,s5,store-rebalancer] 395 +  |   github.com/cockroachdb/cockroach/pkg/kv/kvserver/allocator/storepool/store_pool.go:624
E230206 14:50:58.897133 218 1@util/log/logcrash/crash_reporting.go:188 ⋮ [T1,n5,s5,store-rebalancer] 395 +  | github.com/cockroachdb/cockroach/pkg/kv/kvserver/allocator/storepool.(*StorePool).UpdateLocalStoreAfterRelocate
E230206 14:50:58.897133 218 1@util/log/logcrash/crash_reporting.go:188 ⋮ [T1,n5,s5,store-rebalancer] 395 +  |   github.com/cockroachdb/cockroach/pkg/kv/kvserver/allocator/storepool/store_pool.go:636
E230206 14:50:58.897133 218 1@util/log/logcrash/crash_reporting.go:188 ⋮ [T1,n5,s5,store-rebalancer] 395 +  | github.com/cockroachdb/cockroach/pkg/kv/kvserver.(*StoreRebalancer).PostRangeRebalance
E230206 14:50:58.897133 218 1@util/log/logcrash/crash_reporting.go:188 ⋮ [T1,n5,s5,store-rebalancer] 395 +  |   github.com/cockroachdb/cockroach/pkg/kv/kvserver/pkg/kv/kvserver/store_rebalancer.go:683
E230206 14:50:58.897133 218 1@util/log/logcrash/crash_reporting.go:188 ⋮ [T1,n5,s5,store-rebalancer] 395 +  | github.com/cockroachdb/cockroach/pkg/kv/kvserver.(*StoreRebalancer).rebalanceStore
E230206 14:50:58.897133 218 1@util/log/logcrash/crash_reporting.go:188 ⋮ [T1,n5,s5,store-rebalancer] 395 +  |   github.com/cockroachdb/cockroach/pkg/kv/kvserver/pkg/kv/kvserver/store_rebalancer.go:410
E230206 14:50:58.897133 218 1@util/log/logcrash/crash_reporting.go:188 ⋮ [T1,n5,s5,store-rebalancer] 395 +  | github.com/cockroachdb/cockroach/pkg/kv/kvserver.(*StoreRebalancer).Start.func1
E230206 14:50:58.897133 218 1@util/log/logcrash/crash_reporting.go:188 ⋮ [T1,n5,s5,store-rebalancer] 395 +  |   github.com/cockroachdb/cockroach/pkg/kv/kvserver/pkg/kv/kvserver/store_rebalancer.go:281
E230206 14:50:58.897133 218 1@util/log/logcrash/crash_reporting.go:188 ⋮ [T1,n5,s5,store-rebalancer] 395 +  | github.com/cockroachdb/cockroach/pkg/util/stop.(*Stopper).RunAsyncTaskEx.func2
E230206 14:50:58.897133 218 1@util/log/logcrash/crash_reporting.go:188 ⋮ [T1,n5,s5,store-rebalancer] 395 +  |   github.com/cockroachdb/cockroach/pkg/util/stop/stopper.go:470
E230206 14:50:58.897133 218 1@util/log/logcrash/crash_reporting.go:188 ⋮ [T1,n5,s5,store-rebalancer] 395 +  | runtime.goexit
E230206 14:50:58.897133 218 1@util/log/logcrash/crash_reporting.go:188 ⋮ [T1,n5,s5,store-rebalancer] 395 +  |   GOROOT/src/runtime/asm_amd64.s:1594
E230206 14:50:58.897133 218 1@util/log/logcrash/crash_reporting.go:188 ⋮ [T1,n5,s5,store-rebalancer] 395 +Wraps: (2) runtime error: invalid memory address or nil pointer dereference
E230206 14:50:58.897133 218 1@util/log/logcrash/crash_reporting.go:188 ⋮ [T1,n5,s5,store-rebalancer] 395 +Error types: (1) *withstack.withStack (2) runtime.errorString

Panic is not persistent and starting node again helps.

It seem to be caused by:

StorePool update in allocator:

cockroach/pkg/kv/kvserver/allocator/storepool/store_pool.go

Lines 621 to 627 in 5cf0823

	updateTargets := func(targets []roachpb.ReplicationTarget) {
	for _, target := range targets {
	if toDetail := sp.GetStoreDetailLocked(target.StoreID); toDetail != nil {
	toDetail.Desc.Capacity.RangeCount++
	}
	}
	}

For store which received no gossip info yet.
Existing null check is pointless as GetStoreDetailLocked always returns info, but it could be unpopulated.

Jira issue: CRDB-24266