Don't send pings unless the connection is made

This will hopefully avoid batching tens of ping requests which
we don't care about their results.

telethon/client/updates.py

@@ -335,6 +335,12 @@ class UpdateMethods:
             except Exception:
                 continue  # Any disconnected exception should be ignored
 
+            # Don't bother sending pings until the low-level connection is
+            # ready, otherwise a lot of pings will be batched to be sent upon
+            # reconnect, when we really don't care about that.
+            if not self._sender._transport_connected():
+                continue
+
             # We also don't really care about their result.
             # Just send them periodically.
             try:

telethon/network/mtprotosender.py

@@ -128,6 +128,13 @@ class MTProtoSender:
     def is_connected(self):
         return self._user_connected
 
+    def _transport_connected(self):
+        return (
+            not self._reconnecting
+            and self._connection is not None
+            and self._connection._connected
+        )
+
     async def disconnect(self):
         """
         Cleanly disconnects the instance from the network, cancels