`checkPairwise()` fails when exactly two individuals are typed

[magnusdv]

library(forrel, quietly = T)
x = markerSim(nuclearPed(), N = 10, seed = 123, verbose = F)

# OK with all 3:
checkPairwise(x, plot = F)
#>   id1 id2  N        k0        k1         k2 kappa0 kappa1 kappa2       LR
#> 1   1   2 10 0.9117348 0.0000000 0.08826517      1      0      0 1.088232
#> 2   1   3 10 0.0000000 0.7999559 0.20004411      0      1      0 1.223059
#> 3   2   3 10 0.0000000 0.7999559 0.20004411      0      1      0 1.223059

# Fail:
y = setAlleles(x, ids = 1, alleles = 0)
checkPairwise(y)
#> Error in fix.by(by.y, y): 'by' must match numbers of columns

^{Created on 2022-02-23 by the reprex package (v2.0.1)}