better prune error message (erigontech#2475)

cmd/erigon/main.go

@@ -51,8 +51,13 @@ func runErigon(cliCtx *cli.Context) {
 		chaindb.Close()
 	}
 
-	err := node.New(nodeCfg, ethCfg, logger).Serve()
+	ethNode, err := node.New(nodeCfg, ethCfg, logger)
 	if err != nil {
-		log.Error("error while serving a Erigon node", "err", err)
+		log.Error("Erigon startup", "err", err)
+		return
+	}
+	err = ethNode.Serve()
+	if err != nil {
+		log.Error("error while serving an Erigon node", "err", err)
 	}
 }

eth/backend.go

@@ -231,7 +231,7 @@ func New(stack *node.Node, config *ethconfig.Config, logger log.Logger) (*Ethere
 		if config.Prune.Initialised {
 			// If storage mode is not explicitly specified, we take whatever is in the database
 			if !reflect.DeepEqual(pm, config.Prune) {
-				return errors.New("prune is " + config.Prune.String() + " original prune is " + pm.String())
+				return errors.New("not allowed change of --prune flag, last time you used: " + pm.String())
 			}
 		} else {
 			config.Prune = pm

ethdb/prune/storage_mode.go

@@ -152,33 +152,40 @@ func (m Mode) String() string {
 	if !m.Initialised {
 		return "default"
 	}
-	modeString := ""
+	long := ""
+	short := "--prune="
 	if m.History.Enabled() {
-		modeString += fmt.Sprintf("history=%d,", m.History)
-	} else {
-		modeString += "history=no,"
+		if m.History == params.FullImmutabilityThreshold {
+			short += "h"
+		} else {
+			long += fmt.Sprintf(" --prune.h.older=%d", m.History)
+		}
 	}
 	if m.Receipts.Enabled() {
-		modeString += fmt.Sprintf("receipt=%d,", m.Receipts)
-	} else {
-		modeString += "receipt=no,"
+		if m.Receipts == params.FullImmutabilityThreshold {
+			short += "r"
+		} else {
+			long += fmt.Sprintf(" --prune.r.older=%d", m.Receipts)
+		}
 	}
 	if m.TxIndex.Enabled() {
-		modeString += fmt.Sprintf("txindex=%d,", m.TxIndex)
-	} else {
-		modeString += "txindex=no,"
+		if m.TxIndex == params.FullImmutabilityThreshold {
+			short += "t"
+		} else {
+			long += fmt.Sprintf(" --prune.t.older=%d", m.TxIndex)
+		}
 	}
 	if m.CallTraces.Enabled() {
-		modeString += fmt.Sprintf("calltrace=%d,", m.CallTraces)
-	} else {
-		modeString += "calltrace=no,"
+		if m.CallTraces == params.FullImmutabilityThreshold {
+			short += "c"
+		} else {
+			long += fmt.Sprintf(" --prune.c.older=%d", m.CallTraces)
+		}
 	}
 	if m.Experiments.TEVM {
-		modeString += "experiments.tevm=enabled"
-	} else {
-		modeString += "experiments.tevm=disabled"
+		long += " --experiments.tevm=enabled"
 	}
-	return modeString
+	return short + long
 }
 
 func Override(db kv.RwTx, sm Mode) error {

turbo/node/node.go

@@ -92,20 +92,19 @@ func New(
 	nodeConfig *node.Config,
 	ethConfig *ethconfig.Config,
 	logger log.Logger,
-) *ErigonNode {
+) (*ErigonNode, error) {
 	//prepareBuckets(optionalParams.CustomBuckets)
 	node := makeConfigNode(nodeConfig)
-	ethereum := RegisterEthService(node, ethConfig, logger)
-	return &ErigonNode{stack: node, backend: ethereum}
+	ethereum, err := RegisterEthService(node, ethConfig, logger)
+	if err != nil {
+		return nil, err
+	}
+	return &ErigonNode{stack: node, backend: ethereum}, nil
 }
 
 // RegisterEthService adds an Ethereum client to the stack.
-func RegisterEthService(stack *node.Node, cfg *ethconfig.Config, logger log.Logger) *eth.Ethereum {
-	backend, err := eth.New(stack, cfg, logger)
-	if err != nil {
-		panic(err)
-	}
-	return backend
+func RegisterEthService(stack *node.Node, cfg *ethconfig.Config, logger log.Logger) (*eth.Ethereum, error) {
+	return eth.New(stack, cfg, logger)
 }
 
 func NewNodeConfig() *node.Config {