add staticcheck linting (#3828)

cleanup to add linter

    grpc change:
        https://godoc.org/google.golang.org/grpc#WithContextDialer
        https://godoc.org/google.golang.org/grpc#WithDialer
        grpc/grpc-go#2627
    prometheous change:
        due to UninstrumentedHandler, being deprecated in the future
    empty branch = empty if or else statement
        didn't delete them entirely but commented
        couldn't find a reason to have them
    could not replicate the issue #3406
        but if want to keep it commented then we should comment out the if statement as well

blockchain/v0/reactor.go

@@ -141,9 +141,9 @@ func (bcR *BlockchainReactor) GetChannels() []*p2p.ChannelDescriptor {
 // AddPeer implements Reactor by sending our state to peer.
 func (bcR *BlockchainReactor) AddPeer(peer p2p.Peer) {
 	msgBytes := cdc.MustMarshalBinaryBare(&bcStatusResponseMessage{bcR.store.Height()})
-	if !peer.Send(BlockchainChannel, msgBytes) {
-		// doing nothing, will try later in `poolRoutine`
-	}
+	peer.Send(BlockchainChannel, msgBytes)
+	// it's OK if send fails. will try later in poolRoutine
+
 	// peer is added to the pool once we receive the first
 	// bcStatusResponseMessage from the peer and call pool.SetPeerHeight
 }
@@ -191,18 +191,13 @@ func (bcR *BlockchainReactor) Receive(chID byte, src p2p.Peer, msgBytes []byte)
 
 	switch msg := msg.(type) {
 	case *bcBlockRequestMessage:
-		if queued := bcR.respondToPeer(msg, src); !queued {
-			// Unfortunately not queued since the queue is full.
-		}
+		bcR.respondToPeer(msg, src)
 	case *bcBlockResponseMessage:
 		bcR.pool.AddBlock(src.ID(), msg.Block, len(msgBytes))
 	case *bcStatusRequestMessage:
 		// Send peer our state.
 		msgBytes := cdc.MustMarshalBinaryBare(&bcStatusResponseMessage{bcR.store.Height()})
-		queued := src.TrySend(BlockchainChannel, msgBytes)
-		if !queued {
-			// sorry
-		}
+		src.TrySend(BlockchainChannel, msgBytes)
 	case *bcStatusResponseMessage:
 		// Got a peer status. Unverified.
 		bcR.pool.SetPeerHeight(src.ID(), msg.Height)
@@ -274,9 +269,10 @@ FOR_LOOP:
 				conR, ok := bcR.Switch.Reactor("CONSENSUS").(consensusReactor)
 				if ok {
 					conR.SwitchToConsensus(state, blocksSynced)
-				} else {
-					// should only happen during testing
 				}
+				// else {
+				// should only happen during testing
+				// }
 
 				break FOR_LOOP
 			}

blockchain/v1/reactor.go

@@ -169,9 +169,9 @@ func (bcR *BlockchainReactor) GetChannels() []*p2p.ChannelDescriptor {
 // AddPeer implements Reactor by sending our state to peer.
 func (bcR *BlockchainReactor) AddPeer(peer p2p.Peer) {
 	msgBytes := cdc.MustMarshalBinaryBare(&bcStatusResponseMessage{bcR.store.Height()})
-	if !peer.Send(BlockchainChannel, msgBytes) {
-		// doing nothing, will try later in `poolRoutine`
-	}
+	peer.Send(BlockchainChannel, msgBytes)
+	// it's OK if send fails. will try later in poolRoutine
+
 	// peer is added to the pool once we receive the first
 	// bcStatusResponseMessage from the peer and call pool.updatePeer()
 }
@@ -381,10 +381,11 @@ ForLoop:
 							err:    msg.data.err,
 						},
 					})
-				} else {
-					// For slow peers, or errors due to blocks received from wrong peer
-					// the FSM had already removed the peers
 				}
+				// else {
+				// For slow peers, or errors due to blocks received from wrong peer
+				// the FSM had already removed the peers
+				// }
 			default:
 				bcR.Logger.Error("Event from FSM not supported", "type", msg.event)
 			}
@@ -465,9 +466,10 @@ func (bcR *BlockchainReactor) switchToConsensus() {
 	if ok {
 		conR.SwitchToConsensus(bcR.state, bcR.blocksSynced)
 		bcR.eventsFromFSMCh <- bcFsmMessage{event: syncFinishedEv}
-	} else {
-		// Should only happen during testing.
 	}
+	// else {
+	// Should only happen during testing.
+	// }
 }
 
 // Implements bcRNotifier