Allow type identifier path for extensible variant

[aspeddro]

type A.t += Other

(source_file [0, 0] - [1, 0]
  (ERROR [0, 0] - [0, 4])
  (expression_statement [0, 5] - [0, 17]
    (binary_expression [0, 5] - [0, 17]
      left: (value_identifier_path [0, 5] - [0, 8]
        (module_identifier [0, 5] - [0, 6])
        (value_identifier [0, 7] - [0, 8]))
      (ERROR [0, 10] - [0, 11])
      right: (variant [0, 12] - [0, 17]
        (variant_identifier [0, 12] - [0, 17])))))

Playground Example

[nkrkv]

Thank you!