# XO0201: Result value is never used

Handling errors is mandatory. A `Result` value that is not propagated with `?`, matched, passed, returned, or stored is an error, and so is a `Result` bound to a name that is never used, whatever the name (including `_x`). This covers expression statements, `defer`, loop bodies, `if` without `else`, and the tail of a unit function or closure. The diagnostic offers `?` as a fix. To discard on purpose, write `.ignore_err("reason")`. See core 2.6.

## Example

```xo
enum E { A }

fn g() -> Int ! E { 1 }

fn f() {
  g()
}
```

## Fix

```xo
enum E { A }

fn g() -> Int ! E { 1 }

fn f() ! E {
  g()?
}
```

Run `xo explain XO0201` for this text in a terminal, or see
[section 10.6 of the specification](../../spec/core/#106-diagnostic-codes).