Weird differences in behaviours

boom.go

package main

import "fmt"

func main() {
    const big int = 0x7FFFFFFF/2
    s := [big]int{3}
    fmt.Println(s[big-1])
}

not_boom.go

package main

import "fmt"

func main() {
    const big int = 0x7FFFFFFF/2
    s := [big]int{}
    fmt.Println(s[big-1])
}