check that classes function returns a tuple of length 3

Userconfig/checks.py

@@ -30,7 +30,7 @@ class Checks(object):
             if c.startswith("__"):
                 continue
             ret = getattr(self, c)()
-            if len(ret) == 3:
+            if type(ret) == tuple and len(ret) == 3:
                 classes.append(ret)
         return map(lambda k: (k[1], k[2]), sorted(classes, key=lambda k: k[0]))