[RedTree] add UserFeedbackCheckFailure for app_commands (#6397)

Co-authored-by: Jakub Kuczys <me@jacken.men>

redbot/core/app_commands/__init__.py

@@ -69,6 +69,9 @@ from discord.app_commands import (
 )
 
 from . import checks as checks
+from .errors import (
+    UserFeedbackCheckFailure as UserFeedbackCheckFailure,
+)
 
 __all__ = (
     "AllChannels",
@@ -131,4 +134,5 @@ __all__ = (
     "rename",
     "user_install",
     "checks",
+    "UserFeedbackCheckFailure",
 )

redbot/core/app_commands/errors.py

@@ -0,0 +1,10 @@
+"""Errors module for the app_commands package."""
+from discord import app_commands
+
+
+class UserFeedbackCheckFailure(app_commands.CheckFailure):
+    """A version of CheckFailure responding with a custom error message."""
+
+    def __init__(self, message=None, *args):
+        self.message = message
+        super().__init__(message, *args)

redbot/core/tree.py

@@ -17,6 +17,7 @@ from .app_commands import (
     Group,
     NoPrivateMessage,
     TransformerError,
+    UserFeedbackCheckFailure,
 )
 from .i18n import Translator
 from .utils.chat_formatting import humanize_list, inline
@@ -327,6 +328,9 @@ class RedTree(CommandTree):
                 relative_time=relative_time
             )
             await self._send_from_interaction(interaction, msg, delete_after=error.retry_after)
+        elif isinstance(error, UserFeedbackCheckFailure):
+            if error.message:
+                await self._send_from_interaction(interaction, error.message)
         elif isinstance(error, CheckFailure):
             await self._send_from_interaction(
                 interaction, _("You are not permitted to use this command.")