I tried opening an editor on a non-existing file. It works fine
IFileStore store = EFS.getLocalFileSystem().getStore(new
Path("C:\\NoSuchFile.txt"));
IDE.openEditor(activePage, new FileStoreEditorInput(store),
"org.eclipse.ui.DefaultTextEditor");
So probably the issue would be in your editor. Probably in the place
where you create your model from the file (setInput?), check whether the
file exists and if not, create an empty model.