I am currently encountering the same error in the prebuild v0.109 (20140223_005822).
Specifically, it happens when saving a ship as a blueprint - but only if said ship has weapons linked to computers. The same ship with all weapons unlinked can be saved without problem; saving it with any weapons linked causes the same Critical Error: IllegalArgumentException: null.
Update: The 20140224_030619 build of the prebuild v0.109 still gives the same error under the same circumstances.
Update Two: The 20140225_030748 build of the prebuild v0.11 still does the same.
Update Three: The 20140225_180848 hotfix build of the prebuild v0.111 has solved this problem for me. I can now save ships with linked weapons again without the error mentioned above.
