Missing null check during tree build

[derek-knox]

SirenixTutorialFiles/Data Manager/DataManager.cs

Line 30 in 8c1c96b

tree.AddAllAssetsAtPath(selectedType.Name, "Assets/", selectedType, true, true);

Error when first opening the menu via 'Tools'. A simple null check resolved the issue (I additionally added a sort call as that's likely a default desire):

if (selectedType != null)
{
	tree.AddAllAssetsAtPath(selectedType.Name, "Assets/", selectedType, true, true);
	tree.SortMenuItemsByName(true);
}

[onewheelstudio]

Hmm. Wonder how we missed that one. Thanks. I've updated the code.