Update base.py

Check if data is not None before iterating it on "load" function.

Author: AleixDev

messagebird/base.py

@@ -6,9 +6,10 @@
 
 class Base(object):
     def load(self, data):
-        for name, value in list(data.items()):
-            if hasattr(self, name) and not callable(getattr(self, name)):
-                setattr(self, name, value)
+        if data is not None:
+            for name, value in list(data.items()):
+                if hasattr(self, name) and not callable(getattr(self, name)):
+                    setattr(self, name, value)
 
         return self