Fix, probably, buggy ActionTableModel.

Change-Id: I7f3712e32936e66baac18199f6d702b5b5f66c3b
Reviewed-on: http://gerrit.dmdirc.com/3930
Automatic-Compile: DMDirc Build Manager
Reviewed-by: Chris Smith <chris@dmdirc.com>

ui_swing/src/com/dmdirc/addons/ui_swing/dialogs/actionsmanager/ActionTableModel.java

@@ -26,6 +26,8 @@ import com.dmdirc.actions.Action;
 import com.dmdirc.actions.ActionGroup;
 import com.dmdirc.interfaces.actions.ActionType;
 
+import com.google.common.base.Preconditions;
+
 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.List;
@@ -48,10 +50,8 @@ public class ActionTableModel extends AbstractTableModel {
      * @param actions Actions to show
      */
     public ActionTableModel(final Collection<Action> actions) {
-        this.actions = new ArrayList<>();
-        if (actions != null) {
-            actions.addAll(actions);
-        }
+        Preconditions.checkNotNull(actions);
+        this.actions = new ArrayList<>(actions);
     }
 
     @Override