Process Align Channels: throws recording bug when no channel shift is applied

[tischi]

Pressing OK now throws:

Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
	at de.embl.cba.bdp2.record.ScriptRecorder.<init>(ScriptRecorder.java:90)
	at de.embl.cba.bdp2.record.ScriptRecorder.<init>(ScriptRecorder.java:79)
	at de.embl.cba.bdp2.process.align.channelshift.AlignChannelsDialog.recordMacro(AlignChannelsDialog.java:68)
	at de.embl.cba.bdp2.dialog.AbstractProcessingDialog.ok(AbstractProcessingDialog.java:50)
	at java.util.ArrayList.forEach(ArrayList.java:1257)
	at de.embl.cba.bdp2.dialog.AbstractOkCancelDialog$OkCancelPanel.lambda$new$1(AbstractOkCancelDialog.java:96)
	at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:2022)
	at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2348)
	at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:402)
	at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:259)
	at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonListener.java:252)
	at java.awt.Component.processMouseEvent(Component.java:6533)
	at javax.swing.JComponent.processMouseEvent(JComponent.java:3324)
	at java.awt.Component.processEvent(Component.java:6298)
	at java.awt.Container.processEvent(Container.java:2237)
	at java.awt.Compo