Fix the crash related to the hard-fork change in the peer

eth/protocols/eth/protocol.go

@@ -39,7 +39,7 @@ const c_ProtocolName = "quai"
 
 // ProtocolVersions are the supported versions of the `eth` protocol (first
 // is primary).
-var ProtocolVersions = []uint{QUAI1, QUAI2}
+var ProtocolVersions = []uint{QUAI2}
 
 // protocolLengths are the number of implemented message corresponding to
 // different protocol versions.

p2p/peer.go

@@ -397,6 +397,9 @@ outer:
 func (p *Peer) startProtocols(writeStart <-chan struct{}, writeErr chan<- error) {
 	p.wg.Add(len(p.running))
 	for _, proto := range p.running {
+		if proto == nil {
+			continue
+		}
 		proto := proto
 		proto.closed = p.closed
 		proto.wstart = writeStart
@@ -408,6 +411,9 @@ func (p *Peer) startProtocols(writeStart <-chan struct{}, writeErr chan<- error)
 		p.log.Trace(fmt.Sprintf("Starting protocol %s/%d", proto.Name, proto.Version))
 		go func() {
 			defer p.wg.Done()
+			if proto == nil {
+				return
+			}
 			err := proto.Run(p, rw)
 			if err == nil {
 				p.log.Trace(fmt.Sprintf("Protocol %s/%d returned", proto.Name, proto.Version))