Preventing that crash shouldn't be difficult, but without the tiles, the "correct" behavior of walls would be to slowly die anyway.
Making warptorio teleport the tiles as well doesn't seem easy, especially since the remote interfaces from their FAQ don't seem to exist anymore. In theory, I could probably try packing all the logic into the "on_entity_cloned" event, and use that to also fix up the data structures, but that seems like a lot of work for something that will probably only be relevant for a few weeks until Factorio 2.0 hits.
If warptorio gets updated for Space Age, I'll consider adding that compatibility.
Until then, would you prefer me to fix the crash without making tiles teleportable (walls would just die shortly after teleporting), or to mark warptorio as incompatible?