#5 Crash on empty build.xml

[mmilleder]

When opening a completely empty build.xml, the build
file designer dies because it cannot get a root element:

java.lang.NullPointerException
at
org.vivianj.eclipse.plugin.buildfile.util.BuildFileTree.createTree(BuildFileTree.java:89)
at
org.vivianj.eclipse.plugin.buildfile.editors.BuildFileDesignerEditor.createDesignView(BuildFileDesignerEditor.java:218)
at
org.vivianj.eclipse.plugin.buildfile.editors.BuildFileDesignerEditor.createPages(BuildFileDesignerEditor.java:108)
at
org.eclipse.ui.part.MultiPageEditorPart.createPartControl(MultiPageEditorPart.java:191)
....