(1) The frontend does not allow to create a node with id=0. However, when attempted, it does not say that id=0 is the problem. See cannot-add-node.png.
(2) The frontend, however, allows to edit and save a node with id=0. This node then shows up as shown in id-0-node-list.png and id-0-node-edit.png.
(3) Not related to id=0, but still: when we delete a master node from the child node's frontend, it says "Please be aware that database still contains data related to the deleted Node" (see delete-master-node.png). Is this really true? Does the child node contain any data from the master node? Regardless, the capitalized "Node" should be fixed.