# Unchecked Error Condition (CWE-391)

The product does not properly check when a function or operation returns a value that is associated with an error condition.

**Stack:** Go

- Prevalence: 中 3 言語をカバー
- Impact: ハイ 1 件の重大度ハイのルール
- Prevention: 文書化済み 3 件の修正例

**OWASP:** Insecure Design (A04:2021-Insecure Design) - #4

## Description

When error conditions are not checked, the application may continue with invalid or unexpected state, potentially leading to crashes, data corruption, or security vulnerabilities.

## Prevention

1 件の Shoulder 検出ルールに基づく Unchecked Error Condition の予防策。

### Go

Log or return errors instead of silently swallowing them

## Consequences

- DoS
- 未承認コードの実行
- アプリケーションデータの変更

## Mitigations

- すべての戻り値とエラー条件をチェックする
- 適切な箇所で例外処理を用いる
- 適切なエラーリカバリ機構を実装する

## Detection

- Total rules: 3
- Languages: go, javascript, typescript, python

## Rules by Language

### Go (1 rules)

- **Empty Error Handling** [LOW]: Error check block is empty, silently swallowing errors.
  - Remediation: Log or return errors instead of ignoring them silently.

```go
if err != nil {
    log.Printf("operation failed: %v", err)
    return err
}
```

Learn more: https://shoulder.dev/learn/go/cwe-391/empty-error-handling