That error is related to a BA part.
Same error as Moleman
java.lang.ArrayIndexOutOfBoundsException: -2
at mekhq.campaign.unit.Unit.initializeParts(Unit.java:1805)
at mekhq.campaign.Campaign.createCampaignFromXMLFileInputStream(Campaign.java:4004)
at mekhq.gui.dialog.DataLoadingDialog$Task.doInBackground(DataLoadingDialog.java:184)
at mekhq.gui.dialog.DataLoadingDialog$Task.doInBackground(DataLoadingDialog.java:113)
at javax.swing.SwingWorker$1.call(Unknown Source)
at java.util.concurrent.FutureTask.run(Unknown Source)
at javax.swing.SwingWorker.run(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)