Do I need to CREATE LANGUAGE plpgsql in PostgreSQL 9+

I have a PHP web application using a PostgreSQL database.

Ideally, to install this web application should be easy and only require a database name and user.

Then, the web application loads an SQL file and imports the tables, indices, and functions.

Functions use the plpgsql language.

PostgreSQL 8.4+

At first, the minimum required PostgreSQL version was 8.4.

In order to avoid the #102 error language "plpgsql" does not exist, I was using this at the top of the SQL file:

--
-- Name: create_language_plpgsql(); Type: FUNCTION; Schema: public; Owner: postgres
--

CREATE FUNCTION create_language_plpgsql()
RETURNS BOOLEAN AS $$
    CREATE LANGUAGE plpgsql;
    SELECT TRUE;
$$ LANGUAGE SQL;

SELECT CASE WHEN NOT (
    SELECT TRUE AS exists FROM pg_language
    WHERE lanname='plpgsql'
    UNION
    SELECT FALSE AS exists
    ORDER BY exists DESC
    LIMIT 1
) THEN
    create_language_plpgsql()
ELSE
    FALSE
END AS plpgsql_created;

DROP FUNCTION create_language_plpgsql();

This will create the plpgsql language if it does not exist.

PostgreSQL 9+

Now, I want to drop PostgreSQL 8.4 support.

Judging from the wiki: https://wiki.postgresql.org/wiki/CREATE_OR_REPLACE_LANGUAGE

For PostgreSQL 9.0 and newer [...] "CREATE OR REPLACE LANGUAGE" is the native syntax for installing a procedural language with no error if it's already installed.

So I thought I could replace the above SQL code with

CREATE OR REPLACE LANGUAGE plpgsql;

But when I run this SQL query on a database created on cPanel, I have the following error: ERROR: must be owner of language plpgsql.

Indeed, on cPanel, plpgsql exists, but the user is not the owner of the plpgsql language.

Question

Should I rollback to the old SQL code which was working fine on both PostgreSQL 8.4 and 9+?

Judging from this link, https://www.postgresql.org/docs/9.0/plpgsql-overview.html

In PostgreSQL 9.0 and later, PL/pgSQL is installed by default. However it is still a loadable module, so especially security-conscious administrators could choose to remove it.

Or can I be safe without checking if the plpgsql language exists at all? And assume plpgsql will always be available?