[2.1.9] luaentity::get_filter() returns nil on storage chest ghosts

[Quezler]

- place storage chest ghost
- set a filter
- /c game.print(serpent.block(game.player.selected.get_filter(1)))
- nil

expected behavior: for it to succeed, just like inserters, and reading the filter from ghosts already works.

the this->sections.compiled.empty() check within LogisticPointFilters::getStorageFilter seems to be the culprit, or at least involved.