go菜鸟：请各位大佬指点，代码哪里错了

package main

import (
    "fmt"
    "errors"
    "os"
)

const rows, columns = 9, 9
type Grid [rows][columns]int8

func main() {
    var g Grid
    err := g.Set(6,2,5)
    if err != nil {
        fmt.Println("A",err)
        fmt.Printf("An error occurred: %v.\n", err)
        os.Exit(1)
    }
}

func (g *Grid) Set(row, column int, digit int8) error {
    if !inBounds(row, column) {
        return errors.New("out of bounds")
    }
        g[row][columns] = digit
        return nil

}

func inBounds(row, column int) bool {
    if row < 0 || row >= rows {
        return false
    }

    if column < 0 || column >= columns{
        return false
    }

    return true
}

错误：

#command-line-arguments

./a.go:26:10: invalid argument: array index 9 out of bounds [0:9]