GH-3498: make undefined check explicit
GH-3498: make undefined check explicit

tinymce/tinymce,MediehusetTek/tinymce,gencer/tinymce,leofeyer/tinymce,tinymce/tinymce,leofeyer/tinymce,TeamupCom/tinymce,FernCreek/tinymce,danielpunkass/tinymce,FernCreek/tinymce,adaptiffdesigns/tinymce,danielpunkass/tinymce,MediehusetTek/tinymce,danielpunkass/tinymce,gencer/tinymce,tinymce/tinymce,TeamupCom/tinymce,adaptiffdesigns/tinymce,FernCreek/tinymce