vlib/v/checker/tests/fn_mismatch_option_return_err.vv:4:15: error: cannot use `?time.Duration` as type `time.Duration` in return argument
    2 | 
    3 | fn foo() time.Duration {
    4 |     return ?time.Duration(0)
      |                  ~~~~~~~~~~~
    5 | }
    6 |
