massive ARC bug

[mdsumner]

first arc 0SBAm7 doubles back on itself

set.seed(1)
silicate::ARC(spex::polygonize(raster::raster(matrix(0:1, 2))))$arc_link_vertex
#> # A tibble: 12 x 2
#>    arc_   vertex_
#>    <chr>  <chr>  
#>  1 0SBAm7 kF45Rr 
#>  2 0SBAm7 YgT2Nn 
#>  3 0SBAm7 YgT2Nn 
#>  4 0SBAm7 kF45Rr 
#>  5 1xuGTX YgT2Nn 
#>  6 1xuGTX tT53BF 
#>  7 1xuGTX hJWmVF 
#>  8 1xuGTX kF45Rr 
#>  9 w2au4y kF45Rr 
#> 10 w2au4y kirFsW 
#> 11 w2au4y oObYfy 
#> 12 w2au4y YgT2Nn

^{Created on 2020-10-07 by the reprex package (v0.3.0)}