ERROR: unrecognized configuration parameter "cron.database_name"

When I created the EXTENSION , I reported an error, as follows：

```sql
CREATE EXTENSION pg_cron
> ERROR: unrecognized configuration parameter "cron.database_name"
CONTEXT: PL/pgSQL function inline_code_block line 3 at IF
```

I know it's due to the lack of configuration parameters ("cron.database_name"), but what I'm puzzled by is why an **optionally** parameter would cause an error? Is it because the documentation is wrong, or is it that the code hasn't been compatible with it?

env: pg16.3,pg_cron1.6.7

No file or test is named in the report. Reproduce CREATE EXTENSION pg_cron on PostgreSQL 16.3 with pg_cron 1.6.7, then trace the extension installation and configuration handling. Done means the optional cron.database_name setting no longer causes an installation error, or the documentation clearly states the required configuration.

Written by the indexing model from the issue text.