HexOrDecimal - to accept unquoted numbers - in json (e3) (#11262)

accept in `genesis.json`:` "nonce": 0,`
now see: 
```
Fatal: invalid genesis file: json: cannot unmarshal number into Go struct field Genesis.alloc of type *math.HexOrDecimal64
```

See also `https://github.com/ethereum/go-ethereum/pull/26758`

common/math/big.go

@@ -54,6 +54,17 @@ func NewHexOrDecimal256(x int64) *HexOrDecimal256 {
 	return &h
 }
 
+// UnmarshalJSON implements json.Unmarshaler.
+//
+// It is similar to UnmarshalText, but allows parsing real decimals too, not just
+// quoted decimal strings.
+func (i *HexOrDecimal256) UnmarshalJSON(input []byte) error {
+	if len(input) > 0 && input[0] == '"' {
+		input = input[1 : len(input)-1]
+	}
+	return i.UnmarshalText(input)
+}
+
 // UnmarshalText implements encoding.TextUnmarshaler.
 func (i *HexOrDecimal256) UnmarshalText(input []byte) error {
 	bigint, ok := ParseBig256(string(input))

common/math/integer.go

@@ -46,17 +46,27 @@ const (
 // HexOrDecimal64 marshals uint64 as hex or decimal.
 type HexOrDecimal64 uint64
 
+// UnmarshalJSON implements json.Unmarshaler.
+//
+// It is similar to UnmarshalText, but allows parsing real decimals too, not just
+// quoted decimal strings.
+func (i *HexOrDecimal64) UnmarshalJSON(input []byte) error {
+	if len(input) > 1 && input[0] == '"' {
+		input = input[1 : len(input)-1]
+	}
+	return i.UnmarshalText(input)
+}
+
 // UnmarshalText implements encoding.TextUnmarshaler.
 func (i *HexOrDecimal64) UnmarshalText(input []byte) error {
-	in, ok := ParseUint64(string(input))
+	n, ok := ParseUint64(string(input))
 	if !ok {
 		return fmt.Errorf("invalid hex or decimal integer %q", input)
 	}
-	*i = HexOrDecimal64(in)
+	*i = HexOrDecimal64(n)
 	return nil
 }
 
-// MarshalText implements encoding.TextMarshaler.
 func (i HexOrDecimal64) MarshalText() ([]byte, error) {
 	return []byte(fmt.Sprintf("%#x", uint64(i))), nil
 }

core/genesis_test.go

@@ -18,7 +18,9 @@ package core_test
 
 import (
 	"context"
+	"encoding/json"
 	"math/big"
+	"os"
 	"testing"
 
 	"github.com/holiman/uint256"
@@ -167,3 +169,14 @@ func TestAllocConstructor(t *testing.T) {
 	state.GetState(address, &key1, storage1)
 	assert.Equal(uint256.NewInt(0x01c9), storage1)
 }
+
+// See https://github.com/erigontech/erigon/pull/11264
+func TestDecodeBalance0(t *testing.T) {
+	genesisData, err := os.ReadFile("./genesis_test.json")
+	require.NoError(t, err)
+
+	genesis := &types.Genesis{}
+	err = json.Unmarshal(genesisData, genesis)
+	require.NoError(t, err)
+	_ = genesisData
+}