# AUR4002

## Error Message

`AUR4002: Expected the i18n key to be a string, but got {{value}} of type {{type}}`

## Description

This error occurs when a non-string value is passed as a translation key. The i18n system expects all translation keys to be strings.

## Common Scenarios

```typescript
// ❌ Wrong: Non-string key
const key = 123;
const translated = i18n.tr(key); // AUR4002

// ❌ Wrong: Undefined/null key
const key = undefined;
const translated = i18n.tr(key); // AUR4002
```

## Solution

```typescript
// ✅ Correct: String key
const key = 'welcome';
const translated = i18n.tr(key);

// ✅ Correct: Convert to string if needed
const numericId = 123;
const key = `item_${numericId}`;
const translated = i18n.tr(key);
```