harmony-one/harmony: node/node.go; 27 LoC

Found a possible issue in [harmony-one/harmony](https://www.github.com/harmony-one/harmony) at [node/node.go](https://github.com/harmony-one/harmony/blob/ddf70381a28138d2f65699c678a88e0f003224d1/node/node.go#L965-L991)

Below is the message reported by the analyzer for this snippet of code. Beware that the analyzer only reports the first
issue it finds, so please do not limit your consideration to the contents of the below message.

> range-loop variable doubleSign used in defer or goroutine at line 978

[Click here to see the code in its original context.](https://github.com/harmony-one/harmony/blob/ddf70381a28138d2f65699c678a88e0f003224d1/node/node.go#L965-L991)

Click here to show the 27 line(s) of Go which triggered the analyzer.

```go
for doubleSign := range node.Consensus.SlashChan {
utils.Logger().Info().
RawJSON("double-sign-candidate", []byte(doubleSign.String())).
Msg("double sign notified by consensus leader")
// no point to broadcast the slash if we aren't even in the right epoch yet
if !node.Blockchain().Config().IsStaking(
node.Blockchain().CurrentHeader().Epoch(),
) {
return
}
if hooks := node.NodeConfig.WebHooks.Hooks; hooks != nil {
if s := hooks.Slashing; s != nil {
url := s.OnNoticeDoubleSign
go func() { webhooks.DoPost(url, &doubleSign) }()
}
}
if node.NodeConfig.ShardID != shard.BeaconChainShardID {
go node.BroadcastSlash(&doubleSign)
} else {
records := slash.Records{doubleSign}
if err := node.Blockchain().AddPendingSlashingCandidates(
records,
); err != nil {
utils.Logger().Err(err).Msg("could not add new slash to ending slashes")
}
}
}

```

Leave a reaction on this issue to contribute to the project by classifying this instance as a **Bug** :-1:, **Mitigated** :+1:, or **Desirable Behavior** :rocket:
See the descriptions of the classifications [here](https://github.com/github-vet/rangeclosure-findings#how-can-i-help) for more information.

commit ID: ddf70381a28138d2f65699c678a88e0f003224d1