ices/77218.rs: fixed with errors (rust-lang#520)

=== stdout ===
=== stderr ===
error[E0601]: `main` function not found in crate `77218`
  --> /home/runner/work/glacier/glacier/ices/77218.rs:1:1
   |
1  | / pub struct Cache {
2  | |     data: Vec<i32>,
3  | | }
4  | |
...  |
10 | |     }
11 | | }
   | |_^ consider adding a `main` function to `/home/runner/work/glacier/glacier/ices/77218.rs`

error[E0308]: mismatched types
 --> /home/runner/work/glacier/glacier/ices/77218.rs:7:20
  |
7 |         if /*let*/ Some(reference) = cache.data.get(key) {
  |                    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected `bool`, found `()`
  |
help: you might have meant to use pattern matching
  |
7 |         if /*let*/ let Some(reference) = cache.data.get(key) {
  |                    ^^^

error: aborting due to 2 previous errors

Some errors have detailed explanations: E0308, E0601.
For more information about an error, try `rustc --explain E0308`.
==============

Co-authored-by: rustbot <[email protected]>

Author: github-actions[bot]