PostgreSQL extensions during switchover

Dear all,

I have question regarding how extensions acting during switchover process.

We running PostgreSQL 11 HA primary/replication server that is configured
with repmgr.
Everything works fine but I am interested in matter of how extensions works
during failover/switchover.process.

Let's say:

postgresql.conf configuration file on primary server:

shared_preload_libraries = 'pg_stat_statements,xxxx'

*Contrib package is installed on primary and replication server too.

postgresql.conf configuratioj file on replication server

shared_preload_libraries = '' is empty on replication server.

In case some scenario which will include switchover or failover to
replication server.
How it will act ? Switchover will be successful but new primary node will
fail at startup process because shared_preload_libraries is empty but
extensions are created in database? Or it's better to pre-configure same
extensions into shared_preload_libraries parameter on replication server?

Thank you in advance,
Marian Pompura