remove err p2p node error when use nodiscover add a error 跑

[BiyunZeng]

DEBUG[06-23|14:24:57.916] New tasks discover context="newtasks 0 i 0 lookupBuf 0 needDynDials 0 "
DEBUG[06-23|14:24:57.916] Starting protocol etrue/64 running 1 id=9f5724e32f56dac9 conn=inbound
DEBUG[06-23|14:24:57.916] Truechain peer connected id=9f5724e32f56dac9 conn=inbound name=Getrue/v1.1.0-stable/linux-amd64/go1.12.5 remoteAddr=39.98.240.34:34956
DEBUG[06-23|14:24:57.917] Truechain handshake failed id=9f5724e32f56dac9 conn=inbound err="Genesis block mismatch - df819f11beead767 (!= f82fd9c0c8a53474)"
DEBUG[06-23|14:24:57.917] Start protocols end name=Getrue/v1.1.0-stable/linux-amd64/go1.12.5 err="Genesis block mismatch - df819f11beead767 (!= f82fd9c0c8a53474)" RemoteAddr=39.98.240.34:34956
DEBUG[06-23|14:24:57.917] Read loop read msg name=Getrue/v1.1.0-stable/linux-amd64/go1.12.5 err="read tcp 192.168.14.125:30313->39.98.240.34:34956: use of closed network connection"
DEBUG[06-23|14:24:57.917] Peer quit name=9f5724e32f56dac9 running=1 RemoteAddr=39.98.240.34:34956
DEBUG[06-23|14:24:57.917] ping loop closed name=Getrue/v1.1.0-stable/linux-amd64/go1.12.5
DEBUG[06-23|14:24:57.917] Drop peer name=Getrue/v1.1.0-stable/linux-amd64/go1.12.5 err="Genesis block mismatch - df819f11beead767 (!= f82fd9c0c8a53474)" remoteRequested=false Re
DEBUG[06-23|14:24:57.917] Drop peer name=Getrue/v1.1.0-stable/linux-amd64/go1.12.5 err="Genesis block mismatch - df819f11beead767 (!= f82fd9c0c8a53474)" remoteRequested=false RemoteAddr=39.98.240.34:34956
DEBUG[06-23|14:24:57.917] Removing p2p peer id=9f5724e32f56dac9 conn=inbound duration=495.632µs peers=4 req=false err="Genesis block mismatch - df819f11beead767 (!= f82fd9c0c8a53474)"
panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x20 pc=0xa47fed]

goroutine 54 [running]:
github.com/truechain/truechain-engineering-code/p2p.(*Server).run(0xc0023bef00, 0x144c540, 0xc019d62000)
/root/go/src/github.com/truechain-engineering-code/build/_workspace/src/github.com/truechain/truechain-engineering-code/p2p/server.go:761 +0xbcd
created by github.com/truechain/truechain-engineering-code/p2p.(*Server).Start
/root/go/src/github.com/truechain-engineering-code/build/_workspace/src/github.com/truechain/truechain-engineering-code/p2p/server.go:467 +0x4d5