Inaccurate error message when set fdw batch_size to 0

Hi,

When testing the fdw batch insert, I found a possible issue.

If I set the batch_size to 0 , it will throw an error:

---------------------
CREATE FOREIGN TABLE test(a int, b varchar)
SERVER testserver
OPTIONS (table_name 'testlocal', batch_size '0');
ERROR: fetch_size requires a non-negative integer value
---------------------

The error message here seems not accurate, because
I can see from the code batch_size should be positive ( > 0).

So, is it better to change the error message to “fetch_size requires a positive integer value” ?
I also found fetch_size has the similar issue, attaching a patch to fix this.

Best regards,
houzj