query has no destination for result data

I’m using 10.7. Does an empty result set generate this error by any chance.

One of my plpgsql functions is now throwing this error:
select * from genome_threshold_mono('11-O3C.pbs','1-O3C_chr',1.96, 1000000);
NOTICE: group id is 5eed8d65-d39a-4f72-97a3-ca391b84880d
NOTICE: New threshold: 66128154-d128-4e66-bb8e-e9c9ee5ae89d
NOTICE: doing chrom 11
NOTICE: 2019-03-06 00:21:17.253375-07: markerset id is 9a8f7487-bd64-4d43-9adf-5ae1c6744e60(1-O3C_chr11.Loci.ld), people (5eed8d65-d39a-4f72-97a3-ca391b84880d) id is 11-O3C.pbs
NOTICE: table "collected" does not exist, skipping
NOTICE: table "mrkidx" does not exist, skipping
NOTICE: 2019-03-06 00:21:17.295142-07: working with 28607 markers
NOTICE: 2019-03-06 00:21:17.383835-07: added 3514 segments to imputed_pvalue_t
ERROR: query has no destination for result data
HINT: If you want to discard the results of a SELECT, use PERFORM instead.
CONTEXT: PL/pgSQL function optimal_pvalue_mono(text,text,integer,double precision,integer) line 65 at SQL statement
SQL statement "insert into goptset
select * from optimal_pvalue_mono(people_name, mvec.name, mvec.chrom, conf, maxi)"
PL/pgSQL function genome_pvalue_mono(text,text,double precision,integer) line 19 at SQL statement
SQL statement "insert into threshold_segment(id,threshold_id, segment_id, smooth_pvalue)
select uuid_generate_v4(), tid, f.segment_id, f.pval
from genome_pvalue_mono(pbs_name, markers_rx, conf, maxi) as f"
PL/pgSQL function genome_threshold_mono(text,text,double precision,integer) line 30 at SQL statement

The code referenced at line 65 is the last line in a "for row in query” construct as follows:
54 for segp in
55 select s.id, s.firstmarker, s.lastmarker,
56 v.ipv,
57 array_length(p.probands,1) as pbs,
58 s.lastmarker - s.firstmarker as mks
59 from segment s
60 join imputed_pvalue_t v on s.id = v.segment_id
61 join probandset p on s.probandset_id = p.id
62 join probandset_group_member m on p.id = m.member_id
63 where s.markerset_id = mkset
64 and m.group_id = pbsgid
65 order by ipv, pbs, mks
66 LOOP
Plugging in the appropriate values for an example run generates a proper dataset (~1300 rows)as far as I can tell.
This construct had been working until recent changes but I cannot relate the message to any deformity in the current schema or code.
Any pointers appreciated.