(core): Improve permission error handling.

Add channel permission wards to `LionModule` pre-command hook.
Improve `Forbidden` handling in `embed_reply` and `error_reply` addons.

bot/LionModule.py

@@ -85,6 +85,16 @@ class LionModule(Module):
             if ctx.author.id in ctx.client.objects['ignored_members'][ctx.guild.id]:
                 raise SafeCancellation
 
+            # Check channel permissions are sane
+            if not ctx.ch.permissions_for(ctx.guild.me).send_messages:
+                raise SafeCancellation
+            if not ctx.ch.permissions_for(ctx.guild.me).embed_links:
+                await ctx.reply("I need permission to send embeds in this channel before I can run any commands!")
+                raise SafeCancellation
+
+        # Start typing
+        await ctx.ch.trigger_typing()
+
     async def on_exception(self, ctx, exception):
         try:
             raise exception

bot/utils/ctx_addons.py

@@ -1,6 +1,7 @@
 import asyncio
 import discord
 from cmdClient import Context
+from cmdClient.lib import SafeCancellation
 
 from data import tables
 from core import Lion
@@ -17,9 +18,11 @@ async def embed_reply(ctx, desc, colour=discord.Colour.orange(), **kwargs):
     """
     embed = discord.Embed(description=desc, colour=colour, **kwargs)
     try:
-        return await ctx.reply(embed=embed, reference=ctx.msg)
+        return await ctx.reply(embed=embed, reference=ctx.msg.to_reference(fail_if_not_exists=False))
-    except discord.NotFound:
+    except discord.Forbidden:
-        return await ctx.reply(embed=embed)
+        if not ctx.guild or ctx.ch.permissions_for(ctx.guild.me).send_mssages:
+            await ctx.reply("Command failed, I don't have permission to send embeds in this channel!")
+        raise SafeCancellation
 
 
 @Context.util
@@ -34,15 +37,17 @@ async def error_reply(ctx, error_str, **kwargs):
     )
     message = None
     try:
-        message = await ctx.ch.send(embed=embed, reference=ctx.msg, **kwargs)
+        message = await ctx.ch.send(
-    except discord.NotFound:
+            embed=embed,
-        message = await ctx.ch.send(embed=embed, **kwargs)
+            reference=ctx.msg.to_reference(fail_if_not_exists=False),
-    except discord.Forbidden:
+            **kwargs
-        message = await ctx.reply(error_str)
+        )
-    finally:
-        if message:
         ctx.sent_messages.append(message)
         return message
+    except discord.Forbidden:
+        if not ctx.guild or ctx.ch.permissions_for(ctx.guild.me).send_mssages:
+            await ctx.reply("Command failed, I don't have permission to send embeds in this channel!")
+        raise SafeCancellation
 
 
 @Context.util