p2p/discover: add missing lock when calling tab.handleAddNode (#29960)

p2p/discover/table.go

@@ -452,7 +452,9 @@ func (tab *Table) loadSeedNodes() {
 			addr, _ := seed.UDPEndpoint()
 			tab.log.Trace("Found seed node in database", "id", seed.ID(), "addr", addr, "age", age)
 		}
+		tab.mutex.Lock()
 		tab.handleAddNode(addNodeOp{node: seed, isInbound: false})
+		tab.mutex.Unlock()
 	}
 }