As explained under Helaman 16:10, here in 4 Nephi 1:47 the original text (and apparently the original manuscript) had an instance of the Hebraistic and for the main clause “Amos died” that completes the subordinate after-clause and follows the intervening parenthetical clause (“and the people did still remain in wickedness”). For the latter part of the Book of Mormon text, the 1830 compositor generally deleted such non-English uses of and. For three nearby examples of this editing on his part, see under 3 Nephi 23:8, Mormon 1:5, and Mormon 3:4. The critical text will restore all these original instances of and.
Summary: Restore in 4 Nephi 1:47 the original Hebraistic use of and before the main clause “Amos died”.