# Engine Error, Alpha 23

**URL:** <https://discourse.stonehearth.net/t/engine-error-alpha-23/34097>\
**Category:** Bug Reports\
**Created:** [March 13, 2018, 11:49pm UTC](https://discourse.stonehearth.net/t/engine-error-alpha-23/34097 "2018-03-13T23:49:24Z")\
**Posts on this page:** 2\
**Page:** 1

<div class="post-metadata">

**Author:** ![Bea](https://sea2.discourse-cdn.com/flex022/user_avatar/discourse.stonehearth.net/bea/32/49049_2.png) [@Bea](https://discourse.stonehearth.net/u/Bea)\
**Post date:** [March 13, 2018, 11:49pm UTC](https://discourse.stonehearth.net/t/engine-error-alpha-23/34097/1 "2018-03-13T23:49:24Z")

</div>

**Summary:**  
An engine error came up as I was deleting some farm plots.

release-790 (x64)  
stonehearth/components/crafter/crafter\_component.lua:277: Adding crafted item to pack, but not carrying anything? very odd!  
stack traceback:  
[C]: in function ‘assert’  
stonehearth/components/crafter/crafter\_component.lua:277: in function ‘?’  
stonehearth/ai/actions/call\_method.lua:36: in function \<stonehearth/ai/actions/call\_method.lua:25\>  
[C]: ?  
[C]: ?  
[C]: ?  
[C]: ?  
[C]: in function ‘run’  
stonehearth/services/server/tasks/task\_action.lua:196: in function \<stonehearth/services/server/tasks/task\_action.lua:193\>  
[C]: ?  
[C]: ?  
…  
[C]: in function ‘run’  
stonehearth/components/ai/ai\_component.lua:515: in function \<stonehearth/components/ai/ai\_component.lua:499\>  
[C]: in function ‘xpcall’  
radiant/modules/commons.lua:66: in function ‘xpcall’  
stonehearth/components/ai/ai\_component.lua:499: in function ‘\_thread\_main’  
stonehearth/services/server/threads/thread.lua:273: in function \<stonehearth/services/server/threads/thread.lua:270\>  
[C]: in function ‘xpcall’  
radiant/modules/commons.lua:66: in function ‘xpcall’  
stonehearth/services/server/threads/thread.lua:270: in function ‘f’  
radiant/lib/env.lua:15: in function \<radiant/lib/env.lua:14\>

**Version Number and Mods in use:**  
Alpha 23, release 790, no mods.  
**System Information:**  
Intel® Core™ i3-6100 CPU @ 3.7 Ghz  
8 GB Ram  
64 Bit  
Windows 10

---

<div class="post-metadata">

**Author:** ![Bea](https://sea2.discourse-cdn.com/flex022/user_avatar/discourse.stonehearth.net/bea/32/49049_2.png) [@Bea](https://discourse.stonehearth.net/u/Bea)\
**Post date:** [March 14, 2018, 11:20pm UTC](https://discourse.stonehearth.net/t/engine-error-alpha-23/34097/2 "2018-03-14T23:20:56Z")

</div>

Here’s another. I’d like to know what the issue is, if I can fix it.

release-790 (x64)  
…hearth/components/scaffolding/scaffolding\_region.lua:791: attempt to index field ‘\_owning\_scaffolding’ (a nil value)  
stack traceback:  
radiant/modules/commons.lua:46: in function ‘report\_traceback’  
radiant/modules/commons.lua:57: in function \<radiant/modules/commons.lua:51\>  
…hearth/components/scaffolding/scaffolding\_region.lua:791: in function ‘instance’  
radiant/modules/events.lua:291: in function \<radiant/modules/events.lua:285\>  
[C]: in function ‘xpcall’  
radiant/modules/commons.lua:66: in function ‘xpcall’  
radiant/modules/events.lua:285: in function \<radiant/modules/events.lua:251\>  
[C]: in function ‘destroy\_entity’  
radiant/modules/entities.lua:89: in function ‘destroy\_entity’  
stonehearth/services/server/build/ladder\_builder.lua:140: in function \<stonehearth/services/server/build/ladder\_builder.lua:121\>  
[C]: in function ‘destroy’  
stonehearth/services/server/build/ladder\_manager.lua:71: in function ‘\_destroy\_builder’  
stonehearth/services/server/build/ladder\_builder.lua:466: in function ‘\_check\_if\_valid’  
stonehearth/services/server/build/ladder\_builder.lua:323: in function ‘\_update\_build\_mode’  
stonehearth/services/server/build/ladder\_builder.lua:112: in function \<stonehearth/services/server/build/ladder\_builder.lua:111\>