---
url: https://scruple.dev/plugins/errors.md
---
# Errors

`@scruple/errors` checks error handling and caught failures.

```sh
pnpm add -D @scruple/errors
```

```ts
import { defineConfig } from "@scruple/core";
import { errors } from "@scruple/errors";

export default defineConfig({
  parser,
  provider,
  plugins: { errors: errors() },
  rules: { "errors/no-swallowed-errors": "warn" },
});
```

| Rule                                                                               | Checks                                                    |
| ---------------------------------------------------------------------------------- | --------------------------------------------------------- |
| [`errors/no-swallowed-errors`](#errorsno-swallowed-errors)                         | Unexpected failures silently suppressed by catch handlers |
| [`errors/no-lossy-error-wrapping`](#errorsno-lossy-error-wrapping)                 | Replacement errors that lose the original cause           |
| [`errors/no-message-based-error-dispatch`](#errorsno-message-based-error-dispatch) | Control flow coupled to exception prose                   |
| [`errors/no-useless-catch-boundaries`](#errorsno-useless-catch-boundaries)         | Catch handlers that add no behavior                       |

## `errors/no-swallowed-errors`

Reviews each catch handler with bounded source, imports, surrounding context, calls, and exits. It accepts propagation, observable reporting, cleanup followed by propagation, and visibly intentional recovery or expected-exception fallback. It abstains when an unseen helper may report, propagate, or establish the fallback contract.

Options: `threshold` defaults to `{ warning: 0.9, error: 0.97 }`; `minConfidence` defaults to `0.7`. All three values must be finite values from `0` through `1`.

## `errors/no-lossy-error-wrapping`

Reviews catch handlers with visible non-direct replacement throws. A structured `cause` preserves the original failure; opaque custom wrappers and unresolved constructor behavior cause abstention.

## `errors/no-message-based-error-dispatch`

Reviews direct reads of a catch binding's `message` for branching or classification. Logging, display, and stable structured discriminators are not findings; opaque external classifiers cause abstention.

## `errors/no-useless-catch-boundaries`

Reviews catch handlers that only rethrow the same error without adding recovery, cleanup, reporting, translation, or context. The candidate scope is limited to catches whose behavior is visible; conditional handling and calls to helpers with unresolved effects cause abstention.

```ts
rules: {
  "errors/no-swallowed-errors": [
    "warn",
    { threshold: { warning: 0.95, error: 0.99 } },
  ],
}
```