-- Give run_isok_queries() an IQName that's not on ISOK_QUERIES
-- and see we get a good error message.
SELECT *
  FROM run_isok_queries($$VALUES ('non_existant_iqname')$$);
ERROR:  run_isok_queries: Error executing the supplied argument, which should be an SQL query that returns isok_queries.iqname values
DETAIL:  
The error is: 
Error in run_isok_queries(TEXT)

The detail is:
Supplied query returned a value (non_existant_iqname) that is not an existing ISOK_QUERIES.IQName value

The query is:
VALUES ('non_existant_iqname')

Additional diagnostic information:
PL/pgSQL function run_isok_queries(text) line 69 at RAISE
HINT:  Try executing the SQL query (VALUES ('non_existant_iqname')) and check that it returns the public.isok_queries.iqname values of the queries you wish to run.  Then, call run_isok_queries() with your corrected argument.  (You will probably need to dollar-quote your argument.)
CONTEXT:  PL/pgSQL function run_isok_queries(text) line 442 at RAISE