error[E0046]: not all trait items implemented, missing: `Error`
  --> $DIR/issue-103181-1.rs:12:5
   |
LL |         type Error;
   |         ---------- `Error` from trait
LL |     }
LL |     impl HttpBody for () {
   |     ^^^^^^^^^^^^^^^^^^^^ missing `Error` in implementation

error: aborting due to 1 previous error

For more information about this error, try `rustc --explain E0046`.