Dear Harry,

All printed editions reproduce the passage is as: सागरोंऽशुश्च, e.g. the Poona edition:

Avagraha is historically introduced later. Anusvāra is already represented in the Aśokan Brāhmī script, which means it is an old concept, and represented thereafter in various scripts, whereas svagraha is introduced only much later to Indic scripts. Early manuscripts  frequently do not contain the avagraha sign at all. So, in historically earlier period (when avagraha was no yet there) we would expect to read सागरोंशुश्च, in which the anusvāra would obviously be written over the preceding akṣara. The insertion of the avagraha into this sequence of akṣaras (सागरोंऽशुश्च) should therefore not change much and the anusvāra should remain in its (historically) original place (where it would have been, before the inventions of avagraha).

Regards,

Piotr