error[E0308]: try expression alternatives have incompatible types
  --> $DIR/issue-51632-try-desugar-incompatible-types.rs:8:5
   |
LL |     missing_discourses()?
   |     ^^^^^^^^^^^^^^^^^^^^^ expected enum `std::result::Result`, found `isize`
   |
   = note: expected enum `std::result::Result<isize, ()>`
              found type `isize`
help: try removing this `?`
   |
LL |     missing_discourses()
   |                        --
help: try using a variant of the expected enum
   |
LL |     Ok(missing_discourses()?)
   |

error: aborting due to previous error

For more information about this error, try `rustc --explain E0308`.