A simple circuit of red alloy wire or insulated wire connected to a lantern or an inverted lantern will cause the client to crash when the wire is broken in the powered state.

Isolated ProjectRED and found issue repeatable, tested against 4.2.2.19 and 4.3.2.26 with the latest versions of CodeChickenCore, ForgeMultiPart and Forge 9.11.1.965

Paste of crash report: http://pastebin.com/AudLXHkU

Has nothing to do with the inverted lantern in general. It crashes on several things.
This issue got reported already two months ago, but the op has closed it on accident i guess.
#291

For me it crashes when a MultiPart of any kind is placed next to the active wire when breaking it.
https://github.com/MrTJP/ProjectRed/blob/master/common/mrtjp/projectred/transmission/RedAlloyWirePart.java

It is specifically happening only when multipart lights are connected, and wires are removed. If wires are connected to gates, then nothing happens when the wire is removed. Lights need a rewrite anyway...

FMP issue