handle errors w/ twitter when logging in

routes.py

@@ -36,17 +36,22 @@ def index():
                 settings_error = 'settings_error' in request.args
                 )
     else:
-        return render_template('index.html')
+        return render_template('index.html',
+                twitter_login_error = 'twitter_login_error' in request.args)
 
 @app.route('/login/twitter')
 def twitter_login_step1():
+    try:
         return redirect(lib.twitter.get_login_url(
             callback = url_for('twitter_login_step2', _external=True),
             **app.config.get_namespace("TWITTER_")
             ))
+    except (TwitterError, URLError):
+        return redirect(url_for('index', twitter_login_error='', _anchor='log_in'))
 
 @app.route('/login/twitter/callback')
 def twitter_login_step2():
+    try:
         oauth_token = request.args['oauth_token']
         oauth_verifier = request.args['oauth_verifier']
         token = lib.twitter.receive_verifier(oauth_token, oauth_verifier, **app.config.get_namespace("TWITTER_"))
@@ -63,6 +68,8 @@ def twitter_login_step2():
             httponly=True,
             secure=app.config.get("HTTPS"))
         return resp
+    except (TwitterError, URLError):
+        return redirect(url_for('index', twitter_login_error='', _anchor='log_in'))
 
 @app.route('/upload_tweet_archive', methods=('POST',))
 @require_auth

templates/index.html

@@ -20,7 +20,13 @@
 </section>
 
 <section>
-<h2>Sign in</h2>
+<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?
+</div>
+{% endif %}
+
 <p>Sound good to you? <a href="/login/twitter">Log in with Twitter</a></p>
 </section>
 <section class='policy'>