[FAB-13251] Add nil check in ToGossipMessage

Change-Id: I4b7dac64775107d88b0807a4e5f058222e6b8d2f
Signed-off-by: yacovm <yacovm@il.ibm.com>

Author: yacovm

protos/gossip/extensions.go

@@ -440,6 +440,9 @@ func (m *SignedGossipMessage) IsSigned() bool {
 // SignedGossipMessage out of it.
 // Returns an error if un-marshaling fails.
 func (e *Envelope) ToGossipMessage() (*SignedGossipMessage, error) {
+	if e == nil {
+		return nil, errors.New("nil envelope")
+	}
 	msg := &GossipMessage{}
 	err := proto.Unmarshal(e.Payload, msg)
 	if err != nil {

protos/gossip/extensions_test.go

@@ -26,6 +26,12 @@ import (
 	"github.com/stretchr/testify/assert"
 )
 
+func TestToGossipMessageNilEnvelope(t *testing.T) {
+	memReq := &MembershipRequest{}
+	_, err := memReq.SelfInformation.ToGossipMessage()
+	assert.EqualError(t, err, "nil envelope")
+}
+
 func TestToString(t *testing.T) {
 	// Ensure we don't print the byte content when we
 	// log messages.