swarm, cmd/swarm: address ineffectual assignments (#18048)

* swarm, cmd/swarm: address ineffectual assignments

* swarm/network: remove unused vars from testHandshake

* swarm/storage/feed: revert cursor changes

swarm/state/dbstore.go

@@ -69,7 +69,7 @@ func (s *DBStore) Get(key string, i interface{}) (err error) {
 
 // Put stores an object that implements Binary for a specific key.
 func (s *DBStore) Put(key string, i interface{}) (err error) {
-	bytes := []byte{}
+	var bytes []byte
 
 	marshaler, ok := i.(encoding.BinaryMarshaler)
 	if !ok {

swarm/state/dbstore_test.go

@@ -112,6 +112,9 @@ func testPersistedStore(t *testing.T, store Store) {
 
 	as := []string{}
 	err = store.Get("key2", &as)
+	if err != nil {
+		t.Fatal(err)
+	}
 
 	if len(as) != 3 {
 		t.Fatalf("serialized array did not match expectation")

swarm/state/inmemorystore.go

@@ -59,7 +59,7 @@ func (s *InmemoryStore) Get(key string, i interface{}) (err error) {
 func (s *InmemoryStore) Put(key string, i interface{}) (err error) {
 	s.mu.Lock()
 	defer s.mu.Unlock()
-	bytes := []byte{}
+	var bytes []byte
 
 	marshaler, ok := i.(encoding.BinaryMarshaler)
 	if !ok {