shopspring-numeric extension does not panic on NaN

https://github.com/jackc/pgtype/issues/169

ext/shopspring-numeric/decimal.go

@@ -263,6 +263,16 @@ func (dst *Numeric) DecodeBinary(ci *pgtype.ConnInfo, src []byte) error {
 		return err
 	}
 
+	if num.NaN {
+		return errors.New("cannot decode 'NaN'")
+	}
+	if num.InfinityModifier == pgtype.Infinity {
+		return errors.New("cannot decode 'Infinity'")
+	}
+	if num.InfinityModifier == pgtype.NegativeInfinity {
+		return errors.New("cannot decode '-Infinity'")
+	}
+
 	*dst = Numeric{Decimal: decimal.NewFromBigInt(num.Int, num.Exp), Status: pgtype.Present}
 
 	return nil

ext/shopspring-numeric/decimal_test.go

@@ -1,6 +1,7 @@
 package numeric_test
 
 import (
+	"context"
 	"fmt"
 	"math/big"
 	"math/rand"
@@ -93,6 +94,15 @@ func TestNumericNormalize(t *testing.T) {
 	})
 }
 
+func TestNumericNaN(t *testing.T) {
+	conn := testutil.MustConnectPgx(t)
+	defer testutil.MustCloseContext(t, conn)
+
+	var n shopspring.Numeric
+	err := conn.QueryRow(context.Background(), `select 'NaN'::numeric`).Scan(&n)
+	require.EqualError(t, err, `can't scan into dest[0]: cannot decode 'NaN'`)
+}
+
 func TestNumericTranscode(t *testing.T) {
 	testutil.TestSuccessfulTranscodeEqFunc(t, "numeric", []interface{}{
 		&shopspring.Numeric{Decimal: mustParseDecimal(t, "0"), Status: pgtype.Present},