Add exception raise back when not in pythonista3

Author: M4nw3l

wkwebview.py

@@ -15,8 +15,8 @@
     - Added some better handling for being notified when closing
     - Added some automatic cleanup on close e.g stopping the dispatcher thread
 '''
-
 __version__ = '1.2'
+
 try:
     #pythonista specific libraries
     from objc_util import *