Text.populate_link_offsets(State, line_index)

  if #State.lines ~= #State.line_cache then
    print(('line_cache is out of date; %d when it should be %d'):format(#State.line_cache, #State.lines))
    assert(false)
  end
  if not Text.le1(State.screen_top1, State.cursor1) then
    print(State.screen_top1.line, State.screen_top1.pos, State.cursor1.line, State.cursor1.pos)
    assert(false)
  end

  assert(#State.lines == #State.line_cache, ('line_cache is out of date; %d elements when it should be %d'):format(#State.line_cache, #State.lines))
  assert(Text.le1(State.screen_top1, State.cursor1), ('screen_top (line=%d,pos=%d) is below cursor (line=%d,pos=%d)'):format(State.screen_top1.line, State.screen_top1.pos, State.cursor1.line, State.cursor1.pos))

  assert(#State.lines == #State.line_cache, ('line_cache is out of date; %d elements when it should be %d'):format(#State.line_cache, #State.lines))
  assert(Text.le1(State.screen_top1, State.cursor1), ('screen_top (line=%d,pos=%d) is below cursor (line=%d,pos=%d)'):format(State.screen_top1.line, State.screen_top1.pos, State.cursor1.line, State.cursor1.pos))