Add a special exception for required privileged intents

discord/errors.py

@@ -175,3 +175,27 @@ class ConnectionClosed(ClientException):
         self.reason = ''
         self.shard_id = shard_id
         super().__init__('Shard ID %s WebSocket closed with %s' % (self.shard_id, self.code))
+
+class PrivilegedIntentsRequired(ClientException):
+    """Exception that's thrown when the gateway is requesting privileged intents
+    but they're not ticked in the developer page yet.
+
+    Go to https://discord.com/developers/applications/ and enable the intents
+    that are required. Currently these are as follows:
+
+    - :attr:`Intents.members`
+    - :attr:`Intents.presences`
+
+    Attributes
+    -----------
+    shard_id: Optional[:class:`int`]
+        The shard ID that got closed if applicable.
+    """
+
+    def __init__(self, shard_id):
+        self.shard_id = shard_id
+        msg = 'Shard ID %s is requesting privileged intents that have not been explicitly enabled in the ' \
+              'developer portal. It is recommended to go to https://discord.com/developers/applications/ ' \
+              'and explicitly enable the privileged intents within your application\'s page. If this is not ' \
+              'possible, then consider disabling the privileged intents instead.'
+        super().__init__(msg % shard_id)