require internet, if backend returns falsey assume it was 0 (#687)

require internet, if backend returns falsey assume it was 0

i3pystatus/mail/__init__.py

@@ -59,7 +59,7 @@ class Mail(IntervalModule):
         unread = 0
         current_unread = 0
         for id, backend in enumerate(self.backends):
-            temp = backend.unread
+            temp = backend.unread or 0
             unread = unread + backend.unread
             if id == self.current_backend:
                 current_unread = temp

i3pystatus/mail/imap.py

@@ -1,3 +1,5 @@
+from i3pystatus.core.util import require, internet
+
 try:
     from imaplib2.imaplib2 import IMAP4, IMAP4_SSL
     use_idle = True
@@ -88,6 +90,7 @@ class IMAP(Backend):
         self.last = len(self.connection.search(None, "UnSeen")[1][0].split())
 
     @property
+    @require(internet)
     def unread(self):
         if not use_idle:
             with self.ensure_connection():