Issue description:

Server crash when autocrafting while chunk unloads

What happens:

Server crashes

What you expected to happen:

Server not crashing

Steps to reproduce:

1. Start crafting job
2. walk away from it so the chunk unloads
3. server crashes

Version (make sure you are on the latest version before reporting):

• Minecraft: 1.10.2
• Forge: 12.18.3.2511
• Refined Storage: 1.2.26

Does this issue occur on a server? [yes/no] yes

If a (crash)log is relevant for this issue, link it here:

https://paste.ee/p/fmwdj

Some more info:

https://github.com/raoulvdberge/refinedstorage/blob/mc1.10/src/main/java/com/raoulvdberge/refinedstorage/apiimpl/autocrafting/task/CraftingStep.java#L184-L185

Seems like on your preliminarySteps List there is at least one entry that is null.

You really should point out that you are not supporting 1.10.2 anymore somewhere. I just looked over all your sites and you never mentioned that you are not supporting 1.10.2.

• https://refinedstorage.raoulvdberge.com/community ("We won't accept bug reports for Minecraft 1.10.2.")
• Look through to the 403 "invalid" bugreports on the issue tracker.
• The last RS 1.10 release is from 10 June 2017. That is almost a year.

I'm not going to repeat myself to death with "1.10 is unsupported" with all these obvious factors listed above because you don't want to do any research.