ORA-06531 Reference To Uninitialized Collection When Calling Mosaic

conn scott/tiger
drop table test_rdt;
drop table mosaic_rdt;
drop table test;
drop table mosaic;
create table test (id number primary key, image mdsys.sdo_georaster);
create table mosaic (id number primary key, image mdsys.sdo_georaster);

create table TEST_RDT of mdsys.sdo_raster
(primary key (rasterId, pyramidLevel, bandBlockNumber,
rowBlockNumber, columnBlockNumber))
lob(rasterblock) store as (nocache nologging);

create table MOSAIC_RDT of mdsys.sdo_raster
(primary key (rasterId, pyramidLevel, bandBlockNumber,
rowBlockNumber, columnBlockNumber))
lob(rasterblock) store as (nocache nologging);

declare
gr sdo_georaster;
gr1 sdo_georaster;
gr2 sdo_georaster;

begin
delete from test;
commit;
gr1 := sdo_geor.createBlank(21001, sdo_number_array(0, 0, 0), sdo_number_array(350, 350, 3), 255, 'TEST_RDT');
gr2 := sdo_geor.createBlank(21001, sdo_number_array(0, 0, 0), sdo_number_array(350, 350, 3), 255, 'TEST_RDT');

gr1.spatialExtent := null;
gr2.spatialExtent := null;

sdo_geor.georeference(gr1, 262148, 1,
sdo_number_array(0.419, 0, 1321160.5575),
sdo_number_array(0, -0.419, 467357.1645));
sdo_geor.georeference(gr2, 262148, 1,
sdo_number_array(0.419, 0, 1321244.3575),
sdo_number_array(0, -0.419, 467273.3645));

gr1.spatialExtent := sdo_geor.generateSpatialExtent(gr1);
gr2.spatialExtent := sdo_geor.generateSpatialExtent(gr2);

insert into test (id, image) values (1, gr1);
insert into test (id, image) values (2, gr2);
commit;
delete from mosaic;
commit;
insert into mosaic (id, image) values (1, sdo_geor.init('MOSAIC_RDT')) RETURNING image INTO gr;
sdo_geor.mosaic('TEST', 'IMAGE', gr, NULL);
update mosaic set image = gr where id = 1;
commit;
end;
/

ORA-06531: Reference to uninitialized collection
ORA-06512: at "MDSYS.SDO_GEOR_INT", line 674
ORA-06512: at "MDSYS.SDO_GEOR_INT", line 924
ORA-06512: at "MDSYS.SDO_GEOR_INT", line 1268
ORA-06512: at "MDSYS.SDO_GEOR_INT", line 1539
ORA-06512: at "MDSYS.SDO_GEOR", line 1401