2 files changed, 41 insertions, 3 deletions
diff --git a/bot/exts/backend/error_handler.py b/bot/exts/backend/error_handler.py
index 761991488..f9ded79f0 100644
--- a/bot/exts/backend/error_handler.py
+++ b/bot/exts/backend/error_handler.py
@@ -75,7 +75,7 @@ class ErrorHandler(Cog):
         elif isinstance(e, errors.CheckFailure):
             log.debug(debug_message)
             await self.handle_check_failure(ctx, e)
-        elif isinstance(e, errors.CommandOnCooldown):
+        elif isinstance(e, (errors.CommandOnCooldown, errors.MaxConcurrencyReached)):
             log.debug(debug_message)
             await ctx.send(e)
         elif isinstance(e, errors.CommandInvokeError):
@@ -95,7 +95,7 @@ class ErrorHandler(Cog):
         elif isinstance(e, errors.DisabledCommand):
             log.debug(debug_message)
         else:
-            # MaxConcurrencyReached, ExtensionError
+            # ExtensionError
             await self.handle_unexpected_error(ctx, e)
 
     async def send_command_help(self, ctx: Context) -> None:
@@ -116,9 +116,13 @@ class ErrorHandler(Cog):
         * invoked with `unshh+` unsilence channel
         Return bool depending on success of command.
         """
+        silence_command = self.bot.get_command("silence")
+        if not silence_command:
+            log.debug("Not attempting to parse message as `shh`/`unshh` as could not find `silence` command.")
+            return False
+
         command = ctx.invoked_with.lower()
         args = ctx.message.content.lower().split(" ")
-        silence_command = self.bot.get_command("silence")
         ctx.invoked_from_error_handler = True
 
         try:
@@ -164,6 +168,10 @@ class ErrorHandler(Cog):
         the context to prevent infinite recursion in the case of a CommandNotFound exception.
         """
         tags_get_command = self.bot.get_command("tags get")
+        if not tags_get_command:
+            log.debug("Not attempting to parse message as a tag as could not find `tags get` command.")
+            return
+
         ctx.invoked_from_error_handler = True
 
         log_msg = "Cancelling attempt to fall back to a tag due to failed checks."
diff --git a/bot/exts/backend/security.py b/bot/exts/backend/security.py
new file mode 100644
index 000000000..27e4d9752
--- /dev/null
+++ b/bot/exts/backend/security.py
@@ -0,0 +1,30 @@
+from discord.ext.commands import Cog, Context, NoPrivateMessage
+
+from bot.bot import Bot
+from bot.log import get_logger
+
+log = get_logger(__name__)
+
+
+class Security(Cog):
+    """Security-related helpers."""
+
+    def __init__(self, bot: Bot):
+        self.bot = bot
+        self.bot.check(self.check_not_bot)  # Global commands check - no bots can run any commands at all
+        self.bot.check(self.check_on_guild)  # Global commands check - commands can't be run in a DM
+
+    def check_not_bot(self, ctx: Context) -> bool:
+        """Check if the context is a bot user."""
+        return not ctx.author.bot
+
+    def check_on_guild(self, ctx: Context) -> bool:
+        """Check if the context is in a guild."""
+        if ctx.guild is None:
+            raise NoPrivateMessage("This command cannot be used in private messages.")
+        return True
+
+
+async def setup(bot: Bot) -> None:
+    """Load the Security cog."""
+    await bot.add_cog(Security(bot))