Illegal argument exception if explorer context menu launched prior to explorer view fully functional

Re-opening a workspace with projects and larger model sets will take a little longer to launch.

Right-clicking on the explorer may throw the following because Model Explorer is adding a listener that calls fillContextMenu() on it's own. Need to check that ModelerActionService is fully added/functional.

org.eclipse.core.runtime.AssertionFailedException: null argument:Action must not be null
at org.eclipse.core.runtime.Assert.isNotNull(Assert.java:85)
at org.eclipse.jface.action.ContributionManager.add(ContributionManager.java:76)
at org.teiid.designer.ui.explorer.ModelExplorerResourceNavigator.createRefactorMenu(ModelExplorerResourceNavigator.java:1206)
at org.teiid.designer.ui.explorer.ModelExplorerResourceNavigator.fillContextMenu(ModelExplorerResourceNavigator.java:1291)
at org.teiid.designer.ui.explorer.ModelExplorerResourceNavigator$13.menuAboutToShow(ModelExplorerResourceNavigator.java:1144)
at org.eclipse.jface.action.MenuManager.fireAboutToShow(MenuManager.java:352)
at org.eclipse.jface.action.MenuManager.handleAboutToShow(MenuManager.java:492)
at org.eclipse.jface.action.MenuManager.access$1(MenuManager.java:487)
at org.eclipse.jface.action.MenuManager$2.menuShown(MenuManager.java:519)
at org.eclipse.swt.widgets.TypedListener.handleEvent(TypedListener.java:255)
at org.eclipse.swt.widgets.EventTable.sendEvent(EventTable.java:84)
at org.eclipse.swt.widgets.Display.sendEvent(Display.java:4454)
at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1388)
at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1412)
at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1393)
at org.eclipse.swt.widgets.Menu._setVisible(Menu.java:198)
at org.eclipse.swt.widgets.Display.runPopups(Display.java:3841)
at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:3399)
at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine$9.run(PartRenderingEngine.java:1151)