lint: enable errcheck (#5336)

## Description

Enable errcheck linter throughout the codebase

Closes: #5059

rpc/client/event_test.go

@@ -35,7 +35,11 @@ func TestHeaderEvents(t *testing.T) {
 				// if so, then we start it, listen, and stop it.
 				err := c.Start()
 				require.Nil(t, err, "%d: %+v", i, err)
-				defer c.Stop()
+				t.Cleanup(func() {
+					if err := c.Stop(); err != nil {
+						t.Error(err)
+					}
+				})
 			}
 
 			evtTyp := types.EventNewBlockHeader
@@ -59,14 +63,22 @@ func TestBlockEvents(t *testing.T) {
 				// if so, then we start it, listen, and stop it.
 				err := c.Start()
 				require.Nil(t, err)
-				defer c.Stop()
+				t.Cleanup(func() {
+					if err := c.Stop(); err != nil {
+						t.Error(err)
+					}
+				})
 			}
 
 			const subscriber = "TestBlockEvents"
 
 			eventCh, err := c.Subscribe(context.Background(), subscriber, types.QueryForEvent(types.EventNewBlock).String())
 			require.NoError(t, err)
-			defer c.UnsubscribeAll(context.Background(), subscriber)
+			t.Cleanup(func() {
+				if err := c.UnsubscribeAll(context.Background(), subscriber); err != nil {
+					t.Error(err)
+				}
+			})
 
 			var firstBlockHeight int64
 			for i := int64(0); i < 3; i++ {
@@ -99,7 +111,11 @@ func testTxEventsSent(t *testing.T, broadcastMethod string) {
 				// if so, then we start it, listen, and stop it.
 				err := c.Start()
 				require.Nil(t, err)
-				defer c.Stop()
+				t.Cleanup(func() {
+					if err := c.Stop(); err != nil {
+						t.Error(err)
+					}
+				})
 			}
 
 			// make the tx

rpc/client/helpers.go

@@ -68,7 +68,11 @@ func WaitForOneEvent(c EventsClient, evtTyp string, timeout time.Duration) (type
 		return nil, fmt.Errorf("failed to subscribe: %w", err)
 	}
 	// make sure to unregister after the test is over
-	defer c.UnsubscribeAll(ctx, subscriber)
+	defer func() {
+		if deferErr := c.UnsubscribeAll(ctx, subscriber); deferErr != nil {
+			panic(err)
+		}
+	}()
 
 	select {
 	case event := <-eventCh:

rpc/client/local/local.go

@@ -50,7 +50,9 @@ type Local struct {
 // don't run in parallel, or try to simulate an entire network in
 // one process...
 func New(node *nm.Node) *Local {
-	node.ConfigureRPC()
+	if err := node.ConfigureRPC(); err != nil {
+		node.Logger.Error("Error configuring RPC", "err", err)
+	}
 	return &Local{
 		EventBus: node.EventBus(),
 		Logger:   log.NewNopLogger(),