Fix string literal slicing error (#543)

expr_test.go

@@ -1180,6 +1180,10 @@ func TestExpr(t *testing.T) {
 			`bitushr(-100, 5)`,
 			576460752303423484,
 		},
+		{
+			`"hello"[1:3]`,
+			"el",
+		},
 	}
 
 	for _, tt := range tests {

parser/parser.go

@@ -369,9 +369,8 @@ func (p *parser) parseSecondary() Node {
 		return node
 	case String:
 		p.next()
-		node := &StringNode{Value: token.Value}
+		node = &StringNode{Value: token.Value}
 		node.SetLocation(token.Location)
-		return node
 
 	default:
 		if token.Is(Bracket, "[") {

parser/parser_test.go

@@ -523,6 +523,14 @@ world`},
 				Property: &IntegerNode{Value: 0},
 			},
 		},
+		{
+			`"hello"[1:3]`,
+			&SliceNode{
+				Node: &StringNode{Value: "hello"},
+				From: &IntegerNode{Value: 1},
+				To:   &IntegerNode{Value: 3},
+			},
+		},
 	}
 	for _, test := range tests {
 		t.Run(test.input, func(t *testing.T) {