static get(editor) {
        let result = ObservableCodeEditor._map.get(editor);
        if (!result) {
            result = new ObservableCodeEditor(editor);
            ObservableCodeEditor._map.set(editor, result);
            const d = editor.onDidDispose(() => {
                ObservableCodeEditor._map.delete(editor);
                d.dispose();
            });
        }
        return result;
    }
Make sure that editor is not disposed yet!