CheckErr（err）函数在Golang中崩溃

If I run this code everything works fine and nothing is apparently wrong in the end result (the right id is being printed).

stmt, err := db.Conn.Prepare("INSERT INTO tablename a VALUES (?)")
CheckErr(err)
defer stmt.Close()
res, err := stmt.Exec(&t.Id)
CheckErr(err)

id, err := res.LastInsertId()
fmt.Println(id)

But when I add another CheckErr(err) at the end and I run, I get this:

runtime error: invalid memory address or nil pointer dereference

This is the first thing in the stack trace after the panics:

id, err := res.LastInsertId()

And no id is printed, which is weird since the println comes before the new CheckErr(err)

Any idea why this is happening? I'm clueless

func CheckErr(err error) {
  if err != nil {
    raven.CaptureErrorAndWait(err, nil)
  }
}

CheckErr(err) does not exit or return if err != nil. The program will continue to execute to id, err := res.LastInsertId() and panic if res is nil.