Returning clause in json_table or skip error on error?

I want to convert and insert a local json clob variable into a table like this:

insert into IMP_JSON
select json_name, json_value
from json_table (
    l_clob format json,
    '$[*]' error on error columns (
       json_name          varchar2(32)     path '$.name'          null on empty,
       json_value         varchar2(32)     path '$.value'         null on empty
    )
)

With this code, I get an error message

The provided JavaScript Object Notation (JSON) operator generated a result which exceeds the maximum length specified in the RETURN clause. Increase the maximum size of the data type in the RETURNING clause or use a CLOB or BLOB in the RETURNING clause.

I couldn't find how to include a RETURNING clause in json_table, but if I skip error on error and run the procedure, the resulting table seems complete and not truncated.

1. Why do I get an error message although it works?
2. Is it safe to just remove error on error, or might it truncate the data for other inputs?
3. How can I add a RETURNING clause to json_table?

json_value function you used will return varchar2(4000) by default.

To extend it, you can use returning clause as the error message already suggests. Using returning, your query should be:

INSERT INTO IMP_JSON
SELECT json_name, json_value
FROM json_table (
    l_clob format json,
    '$[*]' error on error columns (
       json_name          varchar2(32000)     path '$.name'          null on empty,
       json_value         varchar2(32000)     path '$.value'         null on empty
    )
);

Another note, if you still get the error

SQL Error: ORA-00910: specified length too long for its datatype

It means your DB parameter max_string_size might be standard.

You can check it:

SELECT name, value
FROM v$parameter
WHERE name = 'max_string_size';

And you might need to set it to extended.