Adding subreddit name to a few error messages.

rtv/content.py

@@ -429,7 +429,10 @@ class SubredditContent(Content):
         try:
             self.get(0)
         except IndexError:
-            raise exceptions.SubredditError('No submissions')
+            full_name = self.name
+            if self.order:
+                full_name += '/' + self.order
+            raise exceptions.NoSubmissionsError(full_name)
 
     @classmethod
     def from_name(cls, reddit, name, loader, order=None, query=None):

rtv/exceptions.py

@@ -22,8 +22,13 @@ class SubmissionError(RTVError):
     "Submission could not be loaded"
 
 
-class SubredditError(RTVError):
-    "Subreddit could not be reached"
+class NoSubmissionsError(RTVError):
+    "No submissions for the given page"
+
+    def __init__(self, name):
+        self.name = name
+        message = '`{0}` has no submissions'.format(name)
+        super(NoSubmissionsError, self).__init__(message)
 
 
 class SubscriptionError(RTVError):

rtv/objects.py

@@ -120,6 +120,7 @@ class LoadScreen(object):
         (praw.errors.OAuthScopeRequired, 'Not logged in'),
         (praw.errors.LoginRequired, 'Not logged in'),
         (praw.errors.InvalidCaptcha, 'Error, captcha required'),
+        (praw.errors.InvalidSubreddit, '{0.args[0]}'),
         (praw.errors.PRAWException, '{0.__class__.__name__}'),
         (requests.exceptions.RequestException, '{0.__class__.__name__}'),
     ]