If user is already muted, send error message to prevent database from screwing up

cogs/moderation.py

@@ -123,6 +123,13 @@ async def mute_members(pool, ctx, targets, reason, muted):
     """
 
     for target in targets:
+        # When user is already muted, send error message
+        if muted in target.roles:
+            embed = Embed(description="**❌ User Is Already Muted! ❌**",
+                          colour=enso_embedmod_colours)
+            await ctx.send(embed=embed)
+
+        else:
             if (ctx.message.guild.me.top_role.position > target.top_role.position
                     and not target.guild_permissions.administrator):