fix #14 Error returning to forget after cancelling authorization

turns out request.args has some special behaviour that forces a 400
instead of throwing a KeyError when trying to read an arg that wasn't
supplied :/ havent seen anything about it in flask's docs

routes/__init__.py

@@ -82,8 +82,8 @@ def login(account_id):
 @app.route('/login/twitter/callback')
 def twitter_login_step2():
     try:
-        oauth_token = request.args['oauth_token']
+        oauth_token = request.args.get('oauth_token', '')
-        oauth_verifier = request.args['oauth_verifier']
+        oauth_verifier = request.args.get('oauth_verifier', '')
         token = libforget.twitter.receive_verifier(
                 oauth_token, oauth_verifier,
                 **app.config.get_namespace("TWITTER_"))
@@ -92,7 +92,7 @@ def twitter_login_step2():
 
         g.viewer = session
         return redirect(url_for('index'))
-    except (TwitterError, URLError):
+    except Exception:
         if sentry:
             sentry.captureException()
         return redirect(

templates/about.html

@@ -23,7 +23,7 @@
 <h2 id="sign_in">Sign in</h2>
 {% if twitter_login_error %}
 <div class="banner error">
-    Sorry, something went wrong when communicating with Twitter. Give it another shot, maybe?
+    Sorry, something went wrong when logging you in with Twitter. Give it another shot, maybe?
 </div>
 {% endif %}