### Before:
return errors when tvf queries an empty file or an error uri:
1. get parsed schema failed, empty csv file
2. Can not get first file, please check uri.
### Now:
we just return empty set when tvf queries an empty file or an error uri.
```sql
mysql> select * from s3(
"uri" = "https://error_uri/exp_1.csv",
"s3.access_key"= "xx",
"s3.secret_key" = "yy",
"format" = "csv") limit 10;
Empty set (1.29 sec)
```
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