Issue description: Game crashes from shift clicking stack of more upgrades than slots

What happens: Simple game crash

What you expected to happen: For the upgrade homes to be filled with the necessary upgrades

Steps to reproduce:

1. Place Importer/Exporter
2. have stack of more upgrades than there are slots
3. Game crash after few second freeze

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

• Minecraft: 1.12.2
• Forge: 14.23.4.2747
• Refined Storage: 1.6

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

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

[https://pastebin.com/4CQyNM3n]

I also didn't know where to ask, but do you plan on doing IC2 Support? Can't connect anything to my MFE or cables. Or charge the portable grid with anything. For now using Energy Networks to workaround, but I want a more organic way to power my storage.

Hold on, I may have forgotten to update the mod itself before reporting...

Alright, so I just needed to update. This can be ignored.