Fixed a zero division error when accessing latencies

When accessing the latencies property on an AutoShardedClient when none of shards are ready, we get a ZeroDivisionError. An example of this can be seen here.
```py
class StatsBot(commands.AutoShardedBot):
    def __init__(self):
        super().__init__(command_prefix=None)
        self._add_commands()

    def _add_commands(self):
        '''Adds commands automatically'''
        for name, attr in inspect.getmembers(self):
            if isinstance(attr, commands.Command):
                self.add_command(attr)
```

When iterating through this custom client's it accesses the latencies property when no shards are ready, therefore it raises the error. A quick fix for this would be to return None if no shards are ready.

0 files changed, 0 insertions, 0 deletions