eth: make tracing API errors more user friendly (#15589)

eth/api.go

@@ -452,7 +452,12 @@ func (api *PrivateDebugAPI) traceBlock(block *types.Block, logConfig *vm.LogConf
 	}
 	statedb, err := blockchain.StateAt(blockchain.GetBlock(block.ParentHash(), block.NumberU64()-1).Root())
 	if err != nil {
-		return false, structLogger.StructLogs(), err
+		switch err.(type) {
+		case *trie.MissingNodeError:
+			return false, structLogger.StructLogs(), fmt.Errorf("required historical state unavailable")
+		default:
+			return false, structLogger.StructLogs(), err
+		}
 	}
 
 	receipts, _, usedGas, err := processor.Process(block, statedb, config)
@@ -518,7 +523,12 @@ func (api *PrivateDebugAPI) TraceTransaction(ctx context.Context, txHash common.
 	}
 	msg, context, statedb, err := api.computeTxEnv(blockHash, int(txIndex))
 	if err != nil {
-		return nil, err
+		switch err.(type) {
+		case *trie.MissingNodeError:
+			return nil, fmt.Errorf("required historical state unavailable")
+		default:
+			return nil, err
+		}
 	}
 
 	// Run the transaction with tracing enabled.