Core - Add invoke error message customisation (#5894)

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

redbot/core/core_commands.py

@@ -3646,7 +3646,7 @@ class Core(commands.commands._RuleDropper, commands.Cog, CoreLogic):
 
     @_set.command(name="usebuttons")
     @checks.is_owner()
-    async def use_buttons(self, ctx: commands.Context, use_buttons: bool = None):
+    async def _set_usebuttons(self, ctx: commands.Context, use_buttons: bool = None):
         """
         Set a global bot variable for using buttons in menus.
 
@@ -3655,7 +3655,7 @@ class Core(commands.commands._RuleDropper, commands.Cog, CoreLogic):
         This defaults to False.
         Using this without a setting will toggle.
 
-         **Examples:**
+        **Examples:**
             - `[p]set usebuttons True` - Enables using buttons.
             - `[p]helpset usebuttons` - Toggles the value.
 
@@ -3670,6 +3670,35 @@ class Core(commands.commands._RuleDropper, commands.Cog, CoreLogic):
         else:
             await ctx.send(_("I will not use buttons on basic menus."))
 
+    @_set.command(name="errormsg")
+    @commands.is_owner()
+    async def _set_errormsg(self, ctx: commands.Context, *, msg: str = None):
+        """
+        Set the message that will be sent on uncaught bot errors.
+
+        To include the command name in the message, use the `{command}` placeholder.
+
+        If you omit the `msg` argument, the message will be reset to the default one.
+
+        **Examples:**
+            - `[p]set errormsg` - Resets the error message back to the default: "Error in command '{command}'.". If the command invoker is one of the bot owners, the message will also include "Check your console or logs for details.".
+            - `[p]set errormsg Oops, the command {command} has failed! Please try again later.` - Sets the error message to a custom one.
+
+        **Arguments:**
+            - `[msg]` - The custom error message. Must be less than 1000 characters. Omit to reset to the default one.
+        """
+        if msg is not None and len(msg) >= 1000:
+            return await ctx.send(_("The message must be less than 1000 characters."))
+
+        if msg is not None:
+            await self.bot._config.invoke_error_msg.set(msg)
+            content = _("Succesfully updated the error message.")
+        else:
+            await self.bot._config.invoke_error_msg.clear()
+            content = _("Successfully reset the error message back to the default one.")
+
+        await ctx.send(content)
+
     @commands.group()
     @checks.is_owner()
     async def helpset(self, ctx: commands.Context):