eth: fix transaction announce/broadcast goroutine leak

eth/peer.go

@@ -157,7 +157,7 @@ func (p *peer) broadcastTransactions() {
 	var (
 		queue []common.Hash         // Queue of hashes to broadcast as full transactions
 		done  chan struct{}         // Non-nil if background broadcaster is running
-		fail  = make(chan error) // Channel used to receive network error
+		fail  = make(chan error, 1) // Channel used to receive network error
 	)
 	for {
 		// If there's no in-flight broadcast running, check if a new one is needed
@@ -219,7 +219,7 @@ func (p *peer) announceTransactions() {
 	var (
 		queue []common.Hash         // Queue of hashes to announce as transaction stubs
 		done  chan struct{}         // Non-nil if background announcer is running
-		fail  = make(chan error) // Channel used to receive network error
+		fail  = make(chan error, 1) // Channel used to receive network error
 	)
 	for {
 		// If there's no in-flight announce running, check if a new one is needed