Spurious incorrect "consider removing this semicolon" help when accessing nonexistent field

[jonas-schievink]

struct S {}

fn f(ctx: &mut S) -> String {
    ctx.sleep = 0;
}

error[E0609]: no field `sleep` on type `&mut S`
 --> src/lib.rs:4:9
  |
4 |     ctx.sleep = 0;
  |         ^^^^^ unknown field

error[E0308]: mismatched types
 --> src/lib.rs:3:22
  |
3 | fn f(ctx: &mut S) -> String {
  |    -                 ^^^^^^ expected struct `std::string::String`, found `()`
  |    |
  |    implicitly returns `()` as its body has no tail or `return` expression
4 |     ctx.sleep = 0;
  |                  - help: consider removing this semicolon

Both of these errors are correct, but the second one should not suggest to remove the semicolon, since that won't fix anything here.