race condition in pgplsql call handler?

I'm looking into PG/PLSql code and following code in
plpgsql_call_handler looks strange:

/* Find or compile the function */
func = plpgsql_compile(fcinfo, false);

/* Mark the function as busy, so it can't be deleted from under
us */
func->use_count++;

I don't have deep knowledge about this part of code. But what happen if
in parallel execution "func" will be deleted between these two lines?

Zdenek