# XO0206: `let _ =` discards a Result; use `.ignore_err("reason")`

`let _ = expr` on a `Result` silently drops its error. Xo requires a reason instead: `expr.ignore_err("why this failure does not matter")` yields `T?` and records the reason, so every discarded error is searchable and reviewable (`xo vet` lists them, XO0208). The diagnostic carries a fix that inserts `.ignore_err("TODO: reason")`. Use `r.ok()` when failure simply means no value. See core 2.6.

## Example

```xo
fn f(fs: Fs) uses fs.write {
  let _ = fs.remove("tmp")
}
```

## Fix

```xo
fn f(fs: Fs) uses fs.write {
  let _ = fs.remove("tmp").ignore_err("best effort temp file cleanup")
}
```

Run `xo explain XO0206` for this text in a terminal, or see
[section 10.6 of the specification](../../spec/core/#106-diagnostic-codes).