Tea treats recoverable failures as typed values. You declare error variants up front, `throw` them from functions that advertise failure, and recover with `catch` plus `case` arms.
## Typed errors and throws
Start by naming the failure cases a function can produce. That keeps the error surface explicit and makes it clear to callers what can go wrong.
```tea
error ConfigError {
Missing(key: String)
}
def require_env(key: String) -> String ! ConfigError.Missing
const value = @env(key)
if value == nil
throw ConfigError.Missing(key)
end
value!
end
```
## Recover errors as values
When you want to turn an error into a regular value, catch it and match the specific variants you care about. Any unmatched path can fall through to a final wildcard arm.
```tea
def describe(path: String) -> String
try read(path) catch err
case is DataError.Missing
`missing:${err.path}`
case is DataError.Permission
"denied"
case _
"unexpected"
end
end
```
-
Declare error variants up front with{" "}
error Name {"{"} ... {"}"}
.
-
Use `throw` from functions that advertise failure in their signature.
- Recover with `catch err` and explicit `case` arms.