cursor: remove redundant check when seek

[BlueBlue-Lee]

It will be checked in Cursor.keyValue func.

func (c *Cursor) keyValue() ([]byte, []byte, uint32) {
	ref := &c.stack[len(c.stack)-1]
	if ref.count() == 0 || ref.index >= ref.count() {
		return nil, nil, 0
	}

	// Retrieve value from node.
	if ref.node != nil {
		inode := &ref.node.inodes[ref.index]
		return inode.key, inode.value, inode.flags
	}

	// Or retrieve value from page.
	elem := ref.page.leafPageElement(uint16(ref.index))
	return elem.key(), elem.value(), elem.flags
}

[codecov-io]

Codecov Report

❗ No coverage uploaded for pull request base (master@d57ee90). Click here to learn what that means.
The diff coverage is n/a.

@@            Coverage Diff            @@
##             master      #75   +/-   ##
=========================================
  Coverage          ?   85.56%           
=========================================
  Files             ?        9           
  Lines             ?     1856           
  Branches          ?        0           
=========================================
  Hits              ?     1588           
  Misses            ?      158           
  Partials          ?      110

Impacted Files	Coverage Δ
cursor.go	95.28% <ø> (ø)

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[heyitsanthony]

nice catch, lgtm

[heyitsanthony]

move this comment down to the keyValue code that does the check so the explanation isn't lost?