ggplot2/ usmapp maps with pattern fill, trying geom_polygon_pattern (updated post!)

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See the FAQ: How to do a minimal reproducible example reprex for beginners. Code examples should permit reproducing the issue by simply cutting and pasting. The nzmap in the code provided produces the error

> nzmap
Error in `get_poly_lengths()`:
! There is a MULTIPOLYGON with length greater than 1