Fix registry loading errors

cogs/plugins.py

@@ -132,8 +132,12 @@ async def cog_load(self):
 
     async def populate_registry(self):
         url = "https://raw.githubusercontent.com/modmail-dev/modmail/master/plugins/registry.json"
-        async with self.bot.session.get(url) as resp:
-            self.registry = json.loads(await resp.text())
+        try:
+            async with self.bot.session.get(url) as resp:
+                self.registry = json.loads(await resp.text())
+        except asyncio.TimeoutError:
+            logger.warn("Failed to fetch registry. Loading with empty registry")
+            self.registry = {}
 
     async def initial_load_plugins(self):
         for plugin_name in list(self.bot.config["plugins"]):
@@ -638,6 +642,14 @@ async def plugins_registry(self, ctx, *, plugin_name: typing.Union[int, str] = N
 
         registry = sorted(self.registry.items(), key=lambda elem: elem[0])
 
+        if registry == {}:
+            embed = discord.Embed(
+                color=self.bot.error_color,
+                description='Registry is empty. This could be because it failed to load.'
+            )
+            await ctx.send(embed=embed)
+            return
+
         if isinstance(plugin_name, int):
             index = plugin_name - 1
             if index < 0: