Fixed errors key missing from session

Added the errors key back into the session flash.
Changed the View errors helper name from ‘bag’  back to ‘errors’

src/masonite/middleware/route/SessionMiddleware.py

@@ -17,7 +17,11 @@ def before(self, request, response):
         request.app.make("request").session = Session
 
         # TODO: Remove in Masonite 5
-        request.app.make("view").share({"bag": MessageBag(Session.get("errors") or {}).helper})
+        bag = MessageBag(Session.get("errors") or {})
+        request.app.make("view").share({"errors": bag.helper})
+        # errors are stored in session flash so 'getting' them actually clears them
+        # so re-add them to the session as a MessageBag
+        Session.flash('errors', bag)
         return request
 
     def after(self, request, _):