error[E0308]: mismatched types
  --> $DIR/issue-3680.rs:3:9
   |
LL |     match None {
   |           ---- this expression has type `Option<_>`
LL |         Err(_) => ()
   |         ^^^^^^ expected `Option<_>`, found `Result<_, _>`
   |
   = note: expected enum `Option<_>`
              found enum `Result<_, _>`
help: try wrapping the pattern in `Some`
   |
LL |         Some(Err(_)) => ()
   |         +++++      +

error: aborting due to 1 previous error

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