Adding NodeModel to NodeLayer set itself as its parent, but NodeModel's parent must be a Diagram

The type the parent of a NodeModel must be a DiagramModel (which is a CanvasModel):

react-diagrams/packages/react-diagrams-core/src/entities/node/NodeModel.ts

Line 21 in a457385

PARENT: DiagramModel;

However, when adding a node to a layer, the layer sets the node's parent to itself:

react-diagrams/packages/react-canvas-core/src/entities/layer/LayerModel.ts

Line 79 in a457385

model.setParent(this);

As LayerModel doesn't inherit from DiagramModel, a class inheriting from NodeModel cannot correctly define its parent type to be a NodeLayerModel (due to the G extends NodeModelGenerics constraint), which is what the parent will actually be at runtime, if the node has been added to a layer.

The above also applies for links.