avoid exceptions when messages/contacts/chats are compared with None

python/src/deltachat/chat.py

@@ -32,6 +32,8 @@ class Chat(object):
         self.id = id
 
     def __eq__(self, other) -> bool:
+        if other is None:
+            return False
         return self.id == getattr(other, "id", None) and self.account._dc_context == other.account._dc_context
 
     def __ne__(self, other) -> bool:

python/src/deltachat/contact.py

@@ -22,7 +22,9 @@ class Contact(object):
         self.account = account
         self.id = id
 
-    def __eq__(self, other):
+    def __eq__(self, other) -> bool:
+        if other is None:
+            return False
         return self.account._dc_context == other.account._dc_context and self.id == other.id
 
     def __ne__(self, other):

python/src/deltachat/message.py

@@ -26,7 +26,9 @@ class Message(object):
         msg_id = self.id
         assert msg_id is not None and msg_id >= 0, repr(msg_id)
 
-    def __eq__(self, other):
+    def __eq__(self, other) -> bool:
+        if other is None:
+            return False
         return self.account == other.account and self.id == other.id
 
     def __repr__(self):