# `type.match_wildcard_required`

Open value space needs a wildcard arm.

Area 3, [Logic](../topics/logic.md); not declinable; the next step is usually the agent's.

```jadpo
function shout(label: Label) -> Label {
    return match label {
        "" -> "unnamed"
    }
}
```

```text
error: This `match` needs a `_` arm
 --> main.jadpo:2:12
  |
2 |     return match label {
  |            ^^^^^^^^^^^ not every value is matched
  reason: `Label` is built on `Text`, so its values can't all be listed; `_` matches every value the arms above it don't.
  next: Add `_ -> ...` as the last arm (agent)
  rule: type.match_wildcard_required
  help: https://jadpo.dev/docs/errors/type.match_wildcard_required

check failed: 1 error, 2 files
```