vlib/v/checker/tests/optional_propagate_nested.vv:10:18: error: to propagate the optional call, `xx_prop` must return an optional
    8 | 
    9 | fn xx_prop() string {
   10 |     s := ret(raise()?)
      |                     ^
   11 |     return s
   12 | }
vlib/v/checker/tests/optional_propagate_nested.vv:28:21: error: to propagate the optional call, `aa_propagate` must return an optional
   26 | 
   27 | fn (mut s St) aa_propagate() {
   28 |     f := retf(s.raise()?)
      |                        ^
   29 |     s.z = 7.5
   30 |     println(f)
