error[E0308]: mismatched types
  --> src/app/cooling_device.rs:38:84
   |
38 |             if let Some(name) = is_system_fan(&device_path).map(|n| n.replace('-', ' ')) {
   |                                                                       -------      ^^^ expected `&str`, found `char`
   |                                                                       |
   |                                                                       arguments to this method are incorrect
   |
note: method defined here
  --> /rustc/129f3b9964af4d4a709d1383930ade12dfe7c081/library/alloc/src/str.rs:271:12
help: if you meant to write a string literal, use double quotes
   |
38 |             if let Some(name) = is_system_fan(&device_path).map(|n| n.replace('-', " ")) {
   |                                                                                    ~ ~