vlib/v/checker/tests/struct_field_mismatch_ref_err.vv:6:23: error: field is not reference but default value is reference
    4 | struct SafeCounter {
    5 | mut:
    6 |     mt sync.Mutex = sync.new_mutex()
      |                          ~~~~~~~~~~~
    7 | pub mut:
    8 |     value map[string]int