Fix antipatterns (#6961)

* Merge variable declaration and assignment
* Use result of type assertion to simplify cases
* Replace call to bytes.Compare with bytes.Equal
* Drop unnecessary use of the blank identifier
* Replace x.Sub(time.Now()) with time.Until(x)
* Function literal can be simplified
* Use a single append to concatenate two slices
* Replace time.Now().Sub(x) with time.Since(x)
* Omit comparison with boolean constant
* Omit redundant nil check on slices
* Nested if can be replaced with else-if
* Function call can be replaced with helper function
* Omit redundant control flow
* Use plain channel send or receive
* Simplify returning boolean expression
* Merge branch 'origin-master' into fix-antipatterns
* Merge branch 'master' into fix-antipatterns
* Merge branch 'origin-master' into revert-single-channel-antipattern
* Revert "Use plain channel send or receive"

This reverts commit b3108fdc3a.

beacon-chain/sync/initial-sync/blocks_fetcher_test.go

@@ -279,23 +279,28 @@ func TestBlocksFetcher_RoundRobin(t *testing.T) {
 				defer cancel()
 				var unionRespBlocks []*eth.SignedBeaconBlock
 
-				for resp := range fetcher.requestResponses() {
-					if resp.err != nil {
-						log.WithError(resp.err).Debug("Block fetcher returned error")
-					} else {
-						unionRespBlocks = append(unionRespBlocks, resp.blocks...)
-						if len(resp.blocks) == 0 {
-							log.WithFields(logrus.Fields{
-								"start": resp.start,
-								"count": resp.count,
-							}).Debug("Received empty slot")
+				for {
+					select {
+					case resp, ok := <-fetcher.requestResponses():
+						if !ok { // channel closed, aggregate
+							return unionRespBlocks, nil
 						}
+
+						if resp.err != nil {
+							log.WithError(resp.err).Debug("Block fetcher returned error")
+						} else {
+							unionRespBlocks = append(unionRespBlocks, resp.blocks...)
+							if len(resp.blocks) == 0 {
+								log.WithFields(logrus.Fields{
+									"start": resp.start,
+									"count": resp.count,
+								}).Debug("Received empty slot")
+							}
+						}
+
+						wg.Done()
 					}
-
-					wg.Done()
 				}
-
-				return unionRespBlocks, nil
 			}
 
 			maxExpectedBlocks := uint64(0)