If one column has different numbers of rows to the rest, sorttable blows up:
imagine a table like
1 2 3 4 5
a b c d e
f g h i j
k l m n o
p
This will cause sorttable to explode with node not found (because
it’ll look for row 4 in column 2 and not find it). Try and cope with this
better (and have the mythical sorttable-debug find it and report it).