Remove itemNil

Never referenced; not sure what it was used for in the past, but it's no
longer.

Author: arp242

lex.go

@@ -13,7 +13,6 @@ type itemType int
 
 const (
 	itemError itemType = iota
-	itemNIL            // used in the parser to indicate no type
 	itemEOF
 	itemText
 	itemString
@@ -1202,8 +1201,6 @@ func (itype itemType) String() string {
 	switch itype {
 	case itemError:
 		return "Error"
-	case itemNIL:
-		return "NIL"
 	case itemEOF:
 		return "EOF"
 	case itemText:

lex_test.go

@@ -22,7 +22,7 @@ func TestPositionString(t *testing.T) {
 }
 
 func TestItemTypeString(t *testing.T) {
-	for _, it := range []itemType{itemError, itemNIL, itemEOF, itemText,
+	for _, it := range []itemType{itemError, itemEOF, itemText,
 		itemString, itemStringEsc, itemRawString, itemMultilineString,
 		itemRawMultilineString, itemBool, itemInteger, itemFloat, itemDatetime,
 		itemArray, itemArrayEnd, itemTableStart, itemTableEnd, itemArrayTableStart,