A computer, that is linked to another (as support/effect) and that has linked module can cause a ghost link.
When you remove this computer by right clicking it will not completely "disappear". The shipcore will have a ghost link on that position the computer was on.
Putting a new but different computer on that exact location, linking it as support/effect will create a second computer in the weapons tab.
{F134}
Using a weapon that has a computer on one of those ghost links can cause a nullpointer when used.
```[2014-12-21 13:24:45] java.lang.NullPointerException
[2014-12-21 13:24:45] at obfuscated.sR.a(SourceFile:477)
[2014-12-21 13:24:45] at obfuscated.kN.a(SourceFile:619)
[2014-12-21 13:24:45] at org.schema.game.common.controller.elements.weapon.WeaponElementManager.handle(SourceFile:131)
[2014-12-21 13:24:45] at org.schema.game.common.controller.elements.ManagerContainer.handle(SourceFile:574)
[2014-12-21 13:24:45] at org.schema.game.common.controller.elements.ShipManagerContainer.handle(SourceFile:414)
[2014-12-21 13:24:45] at obfuscated.wL.a(SourceFile:515)
[2014-12-21 13:24:45] at org.schema.game.common.data.player.ControllerState.handleClientControllerStateFor(SourceFile:148)
[2014-12-21 13:24:45] at org.schema.game.common.data.player.ControllerState.update(SourceFile:586)
[2014-12-21 13:24:45] at org.schema.game.common.data.player.PlayerState.updateLocal(SourceFile:4287)
[2014-12-21 13:24:45] at obfuscated.C.a(SourceFile:3157)
[2014-12-21 13:24:45] at obfuscated.C.update(SourceFile:2758)
[2014-12-21 13:24:45] at obfuscated.Yq.a(SourceFile:1160)
[2014-12-21 13:24:45] at obfuscated.Yq.a(SourceFile:1152)
[2014-12-21 13:24:45] at obfuscated.C.j(SourceFile:2239)
[2014-12-21 13:24:45] at obfuscated.vi.run(SourceFile:76)
[2014-12-21 13:24:45] at java.lang.Thread.run(Unknown Source)
[2014-12-21 13:24:45] [GLFRAME] THROWN: class java.lang.RuntimeException Now Printing StackTrace
[2014-12-21 13:24:45] java.lang.RuntimeException: java.lang.NullPointerException
[2014-12-21 13:24:45] at org.schema.game.common.data.player.PlayerState.updateLocal(SourceFile:4298)
[2014-12-21 13:24:45] at obfuscated.C.a(SourceFile:3157)
[2014-12-21 13:24:45] at obfuscated.C.update(SourceFile:2758)
[2014-12-21 13:24:45] at obfuscated.Yq.a(SourceFile:1160)
[2014-12-21 13:24:45] at obfuscated.Yq.a(SourceFile:1152)
[2014-12-21 13:24:45] at obfuscated.C.j(SourceFile:2239)
[2014-12-21 13:24:45] at obfuscated.vi.run(SourceFile:76)
[2014-12-21 13:24:45] at java.lang.Thread.run(Unknown Source)
```
How to reproduce:
# Get 2 cannon computers and 2 cannon barrels (it doesn't really matter)
# Place 1 cannon computer and 1 cannon barrel down, link them together
# Do the same but for your 2nd computer and barrel
# Link cannon computer 1 to cannon computer 2, or do it via the weapons menu
## remove the support/slaved computer
## press C on the ship core and you'll notice a ghost link on the computer you just removed
## put any other computer in that spot and try to use that as a weapon, you should get nullpointers.