addClass( nodeClass, baseClass, library ) {

		if ( library.has( baseClass ) ) {

			console.warn( `Redefinition of node ${ baseClass.name }` );
			return;

		}

		if ( typeof nodeClass !== 'function' ) throw new Error( `Node class ${ nodeClass.name } is not a class.` );
		if ( typeof baseClass !== 'function' ) throw new Error( `Base class ${ baseClass.name } is not a class.` );

		library.set( baseClass, nodeClass );

	}
Adds a node class definition for the given class definition to the provided type library.

@param {any} nodeClass - The node class definition.
@param {any} baseClass - The class definition.
@param {WeakMap} library - The type library.