lint: enable errcheck (#5336)

## Description

Enable errcheck linter throughout the codebase

Closes: #5059

p2p/conn/connection.go

@@ -336,7 +336,9 @@ func (c *MConnection) _recover() {
 }
 
 func (c *MConnection) stopForError(r interface{}) {
-	c.Stop()
+	if err := c.Stop(); err != nil {
+		c.Logger.Error("Error stopping connection", "err", err)
+	}
 	if atomic.CompareAndSwapUint32(&c.errored, 0, 1) {
 		if c.onError != nil {
 			c.onError(r)

p2p/mock/peer.go

@@ -36,11 +36,13 @@ func NewPeer(ip net.IP) *Peer {
 		kv:   make(map[string]interface{}),
 	}
 	mp.BaseService = service.NewBaseService(nil, "MockPeer", mp)
-	mp.Start()
+	if err := mp.Start(); err != nil {
+		panic(err)
+	}
 	return mp
 }
 
-func (mp *Peer) FlushStop()                              { mp.Stop() }
+func (mp *Peer) FlushStop()                              { mp.Stop() } //nolint:errcheck //ignore error
 func (mp *Peer) TrySend(chID byte, msgBytes []byte) bool { return true }
 func (mp *Peer) Send(chID byte, msgBytes []byte) bool    { return true }
 func (mp *Peer) NodeInfo() p2p.NodeInfo {

p2p/peer_set_test.go

@@ -18,7 +18,7 @@ type mockPeer struct {
 	id ID
 }
 
-func (mp *mockPeer) FlushStop()                              { mp.Stop() }
+func (mp *mockPeer) FlushStop()                              { mp.Stop() } //nolint:errcheck // ignore error
 func (mp *mockPeer) TrySend(chID byte, msgBytes []byte) bool { return true }
 func (mp *mockPeer) Send(chID byte, msgBytes []byte) bool    { return true }
 func (mp *mockPeer) NodeInfo() NodeInfo                      { return DefaultNodeInfo{} }

p2p/pex/addrbook.go

@@ -110,7 +110,7 @@ type addrBook struct {
 
 func newHashKey() []byte {
 	result := make([]byte, highwayhash.Size)
-	crand.Read(result)
+	crand.Read(result) //nolint:errcheck // ignore error
 	return result
 }
 
@@ -328,7 +328,9 @@ func (a *addrBook) MarkGood(id p2p.ID) {
 	}
 	ka.markGood()
 	if ka.isNew() {
-		a.moveToOld(ka)
+		if err := a.moveToOld(ka); err != nil {
+			a.Logger.Error("Error moving address to old", "err", err)
+		}
 	}
 }
 
@@ -373,7 +375,9 @@ func (a *addrBook) ReinstateBadPeers() {
 			continue
 		}
 
-		a.addToNewBucket(ka, bucket)
+		if err := a.addToNewBucket(ka, bucket); err != nil {
+			a.Logger.Error("Error adding peer to new bucket", "err", err)
+		}
 		delete(a.badPeers, ka.ID())
 
 		a.Logger.Info("Reinstated address", "addr", ka.Addr)
@@ -779,7 +783,9 @@ func (a *addrBook) moveToOld(ka *knownAddress) error {
 		if err != nil {
 			return err
 		}
-		a.addToNewBucket(oldest, newBucketIdx)
+		if err := a.addToNewBucket(oldest, newBucketIdx); err != nil {
+			a.Logger.Error("Error adding peer to old bucket", "err", err)
+		}
 
 		// Finally, add our ka to old bucket again.
 		added = a.addToOldBucket(ka, oldBucketIdx)
@@ -935,6 +941,6 @@ func (a *addrBook) hash(b []byte) ([]byte, error) {
 	if err != nil {
 		return nil, err
 	}
-	hasher.Write(b)
+	hasher.Write(b) //nolint:errcheck // ignore error
 	return hasher.Sum(nil), nil
 }

p2p/pex/pex_reactor.go

@@ -171,7 +171,9 @@ func (r *Reactor) OnStart() error {
 
 // OnStop implements BaseService
 func (r *Reactor) OnStop() {
-	r.book.Stop()
+	if err := r.book.Stop(); err != nil {
+		r.Logger.Error("Error stopping address book", "err", err)
+	}
 }
 
 // GetChannels implements Reactor

p2p/test_util.go

@@ -29,7 +29,7 @@ func (ni mockNodeInfo) Validate() error                     { return nil }
 func (ni mockNodeInfo) CompatibleWith(other NodeInfo) error { return nil }
 
 func AddPeerToSwitchPeerSet(sw *Switch, peer Peer) {
-	sw.peers.Add(peer)
+	sw.peers.Add(peer) //nolint:errcheck // ignore error
 }
 
 func CreateRandomPeer(outbound bool) Peer {