coalesce(Int, Utf8) coerces to Int

### Describe the bug

Type coercion of `COALESCE` returns Int even when there are string arguments. This is not always correct, as '' is a valid string but cannot be converted to int. 

### To Reproduce

```sql
SELECT coalesce(1,'')
```

should be typed as a string, not int

### Expected behavior

_No response_

### Additional context

_No response_