Improve IFactory API (#129)

* Improve IFactory API

* Update javascript/src/api.ts

Co-authored-by: Frédéric Collonval <fcollonval@users.noreply.github.com>

Co-authored-by: Frédéric Collonval <fcollonval@users.noreply.github.com>

Author: hbcarlos

javascript/src/api.ts

@@ -47,8 +47,10 @@ export type MapChanges = Map<
 export interface IFactory {
   /**
    * Create a new `ISharedDocument` instance.
+   *
+   * It should return `undefined` if the factory is not able to create a `ISharedDocument`.
    */
-  createNew(options: IFactory.IOptions): ISharedDocument;
+  createNew(options: IFactory.IOptions): ISharedDocument | undefined;
 }
 
 /**

yarn.lock

@@ -596,7 +596,7 @@
     "@jridgewell/sourcemap-codec" "1.4.14"
 
 "@jupyter/ydoc@file:javascript":
-  version "0.3.0-a2"
+  version "0.3.0-a4"
   dependencies:
     "@jupyterlab/nbformat" "^3.0.0 || ^4.0.0-alpha.15"
     "@lumino/coreutils" "^1.11.0 || ^2.0.0-alpha.6"