Improve error message of dynamic fee calculations (#3297)

vms/platformvm/txs/fee/dynamic_calculator.go

@@ -4,11 +4,20 @@
 package fee
 
 import (
+	"errors"
+	"fmt"
+
 	"github.com/ava-labs/avalanchego/vms/components/fee"
 	"github.com/ava-labs/avalanchego/vms/platformvm/txs"
 )
 
-var _ Calculator = (*dynamicCalculator)(nil)
+var (
+	_ Calculator = (*dynamicCalculator)(nil)
+
+	ErrCalculatingComplexity = errors.New("error calculating complexity")
+	ErrCalculatingGas        = errors.New("error calculating gas")
+	ErrCalculatingCost       = errors.New("error calculating cost")
+)
 
 func NewDynamicCalculator(
 	weights fee.Dimensions,
@@ -28,11 +37,27 @@ type dynamicCalculator struct {
 func (c *dynamicCalculator) CalculateFee(tx txs.UnsignedTx) (uint64, error) {
 	complexity, err := TxComplexity(tx)
 	if err != nil {
-		return 0, err
+		return 0, fmt.Errorf("%w: %w", ErrCalculatingComplexity, err)
 	}
 	gas, err := complexity.ToGas(c.weights)
 	if err != nil {
-		return 0, err
+		return 0, fmt.Errorf(
+			"%w with complexity (%v) and weights (%v): %w",
+			ErrCalculatingGas,
+			complexity,
+			c.weights,
+			err,
+		)
+	}
+	fee, err := gas.Cost(c.price)
+	if err != nil {
+		return 0, fmt.Errorf(
+			"%w with gas (%d) and price (%d): %w",
+			ErrCalculatingCost,
+			gas,
+			c.price,
+			err,
+		)
 	}
-	return gas.Cost(c.price)
+	return fee, nil
 }