🐛 [Bug]: Mention，文档demo报错

### Version

1.5.5

### Vue Version

3.3.4

### Link to minimal reproduction

文档demo报错，`TypeError: Cannot read properties of undefined (reading 'length')`

### Step to reproduce

文档demo报错，`TypeError: Cannot read properties of undefined (reading 'length')`

### What is expected

_No response_

### What is actually happening

_No response_

### Any additional comments (optional)

_No response_