JsModule {
    bom_token: missing (optional),
    interpreter_token: missing (optional),
    directives: JsDirectiveList [],
    items: JsModuleItemList [
        JsExpressionStatement {
            expression: JsSequenceExpression {
                left: JsSequenceExpression {
                    left: JsSequenceExpression {
                        left: JsNumberLiteralExpression {
                            value_token: JS_NUMBER_LITERAL@0..1 "1" [] [],
                        },
                        comma_token: COMMA@1..3 "," [] [Whitespace(" ")],
                        right: JsNumberLiteralExpression {
                            value_token: JS_NUMBER_LITERAL@3..4 "2" [] [],
                        },
                    },
                    comma_token: COMMA@4..6 "," [] [Whitespace(" ")],
                    right: missing (required),
                },
                comma_token: COMMA@6..8 "," [] [Whitespace(" ")],
                right: JsNumberLiteralExpression {
                    value_token: JS_NUMBER_LITERAL@8..9 "4" [] [],
                },
            },
            semicolon_token: missing (optional),
        },
    ],
    eof_token: EOF@9..10 "" [Newline("\n")] [],
}

0: JS_MODULE@0..10
  0: (empty)
  1: (empty)
  2: JS_DIRECTIVE_LIST@0..0
  3: JS_MODULE_ITEM_LIST@0..9
    0: JS_EXPRESSION_STATEMENT@0..9
      0: JS_SEQUENCE_EXPRESSION@0..9
        0: JS_SEQUENCE_EXPRESSION@0..6
          0: JS_SEQUENCE_EXPRESSION@0..4
            0: JS_NUMBER_LITERAL_EXPRESSION@0..1
              0: JS_NUMBER_LITERAL@0..1 "1" [] []
            1: COMMA@1..3 "," [] [Whitespace(" ")]
            2: JS_NUMBER_LITERAL_EXPRESSION@3..4
              0: JS_NUMBER_LITERAL@3..4 "2" [] []
          1: COMMA@4..6 "," [] [Whitespace(" ")]
          2: (empty)
        1: COMMA@6..8 "," [] [Whitespace(" ")]
        2: JS_NUMBER_LITERAL_EXPRESSION@8..9
          0: JS_NUMBER_LITERAL@8..9 "4" [] []
      1: (empty)
  4: EOF@9..10 "" [Newline("\n")] []
--
sequence_expr.js:1:7 parse ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  × Expected an expression but instead found ','.
  
  > 1 │ 1, 2, , 4
      │       ^
    2 │ 
  
  i Expected an expression here.
  
  > 1 │ 1, 2, , 4
      │       ^
    2 │ 
  
--
1, 2, , 4