Fix nil errors

[Astralcircle]

Fixes:

[Contraption Framework] lua/cfw/core/connectivity_sv.lua:16: bad argument #1 to 'pairs' (table expected, got nil)
1. pairs - [C]:-1
 2. floodFill - lua/cfw/core/connectivity_sv.lua:16
  3. disconnect - lua/cfw/core/connectivity_sv.lua:76
   4. fn - lua/cfw/core/parenting_sv.lua:107
    5. unknown - addons/ulib-master/lua/ulib/shared/hook.lua:109

[Contraption Framework] lua/cfw/core/connectivity_sv.lua:68: attempt to index field '_links' (a nil value)
1. disconnect - lua/cfw/core/connectivity_sv.lua:68
 2. SetParent - lua/cfw/core/parenting_sv.lua:63
  3. Function - lua/autorun/parent_childtables.lua:26
   4. fn - lua/includes/extensions/entity.lua:146
    5. unknown - addons/ulib-master/lua/ulib/shared/hook.lua:109

[thecraftianman]

iirc we purposely haven't fixed these yet because they've consistently indicated deeper issues with how certain entities are being handled. Do you think you could please give some more context behind what was causing these?

[Astralcircle]

No, my server just had error logging and they were occurring, but it seems my pull didn't help as they still occur occasionally.