all: simplify switches (#17267)

* all: simplify switches

* silly mistake

eth/filters/filter_system.go

@@ -338,8 +338,7 @@ func (es *EventSystem) broadcast(filters filterIndex, ev interface{}) {
 			}
 		}
 	case *event.TypeMuxEvent:
-		switch muxe := e.Data.(type) {
-		case core.PendingLogsEvent:
+		if muxe, ok := e.Data.(core.PendingLogsEvent); ok {
 			for _, f := range filters[PendingLogsSubscription] {
 				if e.Time.After(f.created) {
 					if matchedLogs := filterLogs(muxe.Logs, nil, f.logsCrit.ToBlock, f.logsCrit.Addresses, f.logsCrit.Topics); len(matchedLogs) > 0 {

eth/handler.go

@@ -744,8 +744,7 @@ func (pm *ProtocolManager) BroadcastTxs(txs types.Transactions) {
 func (pm *ProtocolManager) minedBroadcastLoop() {
 	// automatically stops if unsubscribe
 	for obj := range pm.minedBlockSub.Chan() {
-		switch ev := obj.Data.(type) {
-		case core.NewMinedBlockEvent:
+		if ev, ok := obj.Data.(core.NewMinedBlockEvent); ok {
 			pm.BroadcastBlock(ev.Block, true)  // First propagate block to peers
 			pm.BroadcastBlock(ev.Block, false) // Only then announce to the rest
 		}

eth/tracers/tracer.go

@@ -486,12 +486,7 @@ func (jst *Tracer) call(method string, args ...string) (json.RawMessage, error)
 }
 
 func wrapError(context string, err error) error {
-	var message string
-	switch err := err.(type) {
-	default:
-		message = err.Error()
-	}
-	return fmt.Errorf("%v    in server-side tracer function '%v'", message, context)
+	return fmt.Errorf("%v    in server-side tracer function '%v'", err, context)
 }
 
 // CaptureStart implements the Tracer interface to initialize the tracing operation.