When I place a cable from Integrated Dynamics next to a Chemical Reactor from NuclearCraft, the entire game crashes and the world can no longer be opened. This only happens when Mekanism is installed as well.

I looked into the code and found the crash occurs here because asking a capability for their default instance may throw a InstantiationException or a IllegalAccessException (see the capability factory in the CapabilityManager class) that isn't caught. The capability that is queried is ICable from Integrated Dynamics which has an abstract default implementation and therefore can't be instantiated. This of course is a mistake in itself, but NuclearCraft should guard against those Exceptions anyways.

Information
Minecraft: 1.12.2
Forge: 14.23.4.2705
NuclearCraft: 2.12e
Other Mods:
Mekanism 1.12.2-9.4.13.349
Integrated Dynamics 0.11.17
Cyclops Core 0.11.10
Common Capabilities 1.4.0
JEI 4.13.1.220

Crash Report here

Ah, thanks very much for pointing that out - will get that sorted!

Fixed for next build :)