crypto.go:147: invalid memory address or nil pointer dereference

[xaionaro]

~/go/src/github.com/wkoomson/go-i2cp$ go test
Loading config file [/home/********/.i2cp.conf]
open /home/********/.i2cp.conf: no such file or directory
%!(EXTRA []interface {}=[])Client connecting to i2cp at [127.0.0.1 127.0.0.1]:%!s(MISSING)
Sending protocol byte message
[...]
Stream len 387 
Sending CreateSessionMessage
%!(EXTRA []interface {}=[])Writing [4] options to mapping table
--- FAIL: TestClient_CreateSession (0.08s)
panic: runtime error: invalid memory address or nil pointer dereference [recovered]
	panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x10 pc=0x50e2c6]

goroutine 6 [running]:
testing.tRunner.func1(0xc4200d21e0)
	/usr/lib/go-1.10/src/testing/testing.go:742 +0x29d
panic(0x61a6e0, 0x77eff0)
	/usr/lib/go-1.10/src/runtime/panic.go:502 +0x229
math/big.(*Int).Bytes(0x0, 0xc400000000, 0x0, 0x0)
	/usr/lib/go-1.10/src/math/big/int.go:434 +0x26
github.com/wkoomson/go-i2cp.(*Crypto).WriteSignatureToStream(0x788aa0, 0xc4201541c8, 0xc42000e068, 0x0, 0x1c)
	/home/********/go/src/github.com/wkoomson/go-i2cp/crypto.go:147 +0x56
github.com/wkoomson/go-i2cp.(*SessionConfig).writeToMessage(0xc420001980, 0xc42000e068)
	/home/********/go/src/github.com/wkoomson/go-i2cp/session_config.go:107 +0xf8
github.com/wkoomson/go-i2cp.(*Client).msgCreateSession(0xc4200d6100, 0xc420001980, 0x0)
	/home/********/go/src/github.com/wkoomson/go-i2cp/client.go:469 +0x8a
github.com/wkoomson/go-i2cp.(*Client).CreateSession(0xc4200d6100, 0xc42000c4c0)
	/home/********/go/src/github.com/wkoomson/go-i2cp/client.go:554 +0xa1
github.com/wkoomson/go-i2cp.TestClient_CreateSession(0xc4200d21e0)
	/home/********/go/src/github.com/wkoomson/go-i2cp/client_test.go:31 +0x15e
testing.tRunner(0xc4200d21e0, 0x668458)
	/usr/lib/go-1.10/src/testing/testing.go:777 +0xd0
created by testing.(*T).Run
	/usr/lib/go-1.10/src/testing/testing.go:824 +0x2e0
exit status 2