Although it's the caller's duty to avoid WSClient re-closing, we
still can handle it.
Fixes the following neofs-node error:
```
panic: close of closed channel
goroutine 98 [running]:
github.com/nspcc-dev/neo-go/pkg/rpc/client.(*WSClient).Close(...)
github.com/nspcc-dev/neo-go@v0.98.3-pre.0.20220321144433-3b639f518ebb/pkg/rpc/client/wsclient.go:120
github.com/nspcc-dev/neofs-node/pkg/morph/subscriber.(*subscriber).Close(0x13)
github.com/nspcc-dev/neofs-node/pkg/morph/subscriber/subscriber.go:108 +0x29
github.com/nspcc-dev/neofs-node/pkg/morph/event.listener.Stop(...)
github.com/nspcc-dev/neofs-node/pkg/morph/event/listener.go:573
created by github.com/nspcc-dev/neofs-node/pkg/innerring.(*Server).Stop
github.com/nspcc-dev/neofs-node/pkg/innerring/innerring.go:285 +0x12f
```
Fix the following linter warning:
```
pkg/rpc/client/wsclient.go:99:18 govet copylocks: literal copies lock value from *cl: github.com/nspcc-dev/neo-go/pkg/rpc/client.Client contains sync.RWMutex
```
1. Keep initDone check only for the places where cache is directly accessed.
We don't need to check it in other places, otherwise we have a mess of
duplicating checks.
2. Fix bug in code related to block deserialisation. There's no magic, so
checking that initialisation is done is not enough for proper block
deserialisation. We need to manually fill StateRootEnabled field.
3. Since transaction doesn't need network magic to compute its hash, we don't
need to perform Client initialisation before transaction-related requests.
4. Check that cache is initialised before accessing network magic.
5. Refactor the way Policy contract hash is fetched for Client requests.
We don't really need Client initialisation for that, it's OK to fetch Policy
hash on-the-fly.
1. Use empty `prefix` instead of nil `preifx` in order to avoid RPC server
exceptions.
2. Allow to omit `start` parameter` if `maxCount` is not specified.
3. Use empty `start` instead of nil `start` to avoid RPC server
exceptions.
Copying just the scope doesn't work for CustomContracts, CustomGroups and
Rules because they all contain additional metadata. Thanks @mialbu for
reporting this.
Standards are NEP-11 and NEP-17, not NEP11, not NEP17, not anything
else. Variable/function names of course can use whatever fits, but documents
and comments should be consistent wrt this.
`StateRootInHeader` is duplicated similarly to `Network`.
It will be removed in future as it is surely a protocol parameter.
Signed-off-by: Evgeniy Stratonikov <evgeniy@nspcc.ru>
