lint: enable errcheck (#5336)

## Description

Enable errcheck linter throughout the codebase

Closes: #5059

blockchain/v0/pool.go

@@ -214,7 +214,9 @@ func (pool *BlockPool) PopRequest() {
 			PanicSanity("PopRequest() requires a valid block")
 		}
 		*/
-		r.Stop()
+		if err := r.Stop(); err != nil {
+			pool.Logger.Error("Error stopping requester", "err", err)
+		}
 		delete(pool.requesters, pool.height)
 		pool.height++
 	} else {
@@ -615,7 +617,9 @@ OUTER_LOOP:
 		for {
 			select {
 			case <-bpr.pool.Quit():
-				bpr.Stop()
+				if err := bpr.Stop(); err != nil {
+					bpr.Logger.Error("Error stopped requester", "err", err)
+				}
 				return
 			case <-bpr.Quit():
 				return

blockchain/v0/reactor.go

@@ -129,7 +129,9 @@ func (bcR *BlockchainReactor) SwitchToFastSync(state sm.State) error {
 // OnStop implements service.Service.
 func (bcR *BlockchainReactor) OnStop() {
 	if bcR.fastSync {
-		bcR.pool.Stop()
+		if err := bcR.pool.Stop(); err != nil {
+			bcR.Logger.Error("Error stopping pool", "err", err)
+		}
 	}
 }
 
@@ -313,7 +315,9 @@ FOR_LOOP:
 				"outbound", outbound, "inbound", inbound)
 			if bcR.pool.IsCaughtUp() {
 				bcR.Logger.Info("Time to switch to consensus reactor!", "height", height)
-				bcR.pool.Stop()
+				if err := bcR.pool.Stop(); err != nil {
+					bcR.Logger.Error("Error stopping pool", "err", err)
+				}
 				conR, ok := bcR.Switch.Reactor("CONSENSUS").(consensusReactor)
 				if ok {
 					conR.SwitchToConsensus(state, blocksSynced > 0 || stateSynced)

blockchain/v2/reactor.go

@@ -318,7 +318,9 @@ func (r *BlockchainReactor) demux(events <-chan Event) {
 		case <-doProcessBlockCh:
 			r.processor.send(rProcessBlock{})
 		case <-doStatusCh:
-			r.io.broadcastStatusRequest()
+			if err := r.io.broadcastStatusRequest(); err != nil {
+				r.logger.Error("Error broadcasting status request", "err", err)
+			}
 
 		// Events from peers. Closing the channel signals event loop termination.
 		case event, ok := <-events:
@@ -343,9 +345,13 @@ func (r *BlockchainReactor) demux(events <-chan Event) {
 				r.processor.send(event)
 			case scPeerError:
 				r.processor.send(event)
-				r.reporter.Report(behaviour.BadMessage(event.peerID, "scPeerError"))
+				if err := r.reporter.Report(behaviour.BadMessage(event.peerID, "scPeerError")); err != nil {
+					r.logger.Error("Error reporting peer", "err", err)
+				}
 			case scBlockRequest:
-				r.io.sendBlockRequest(event.peerID, event.height)
+				if err := r.io.sendBlockRequest(event.peerID, event.height); err != nil {
+					r.logger.Error("Error sending block request", "err", err)
+				}
 			case scFinishedEv:
 				r.processor.send(event)
 				r.scheduler.stop()

blockchain/v2/scheduler.go

@@ -288,7 +288,9 @@ func (sc *scheduler) setPeerRange(peerID p2p.ID, base int64, height int64) error
 	}
 
 	if height < peer.height {
-		sc.removePeer(peerID)
+		if err := sc.removePeer(peerID); err != nil {
+			return err
+		}
 		return fmt.Errorf("cannot move peer height lower. from %d to %d", peer.height, height)
 	}
 
@@ -611,7 +613,9 @@ func (sc *scheduler) handleTryPrunePeer(event rTryPrunePeer) (Event, error) {
 		// from that peer within sc.peerTimeout. Remove the peer. This is to ensure that a peer
 		// will be timed out even if it sends blocks at higher heights but prevents progress by
 		// not sending the block at current height.
-		sc.removePeer(sc.pendingBlocks[sc.height])
+		if err := sc.removePeer(sc.pendingBlocks[sc.height]); err != nil {
+			return nil, err
+		}
 	}
 
 	prunablePeers := sc.prunablePeers(sc.peerTimeout, sc.minRecvRate, event.time)