Change invalid command handling

[simshadows]

Currently (as far as I can tell), all invalid commands are replied to in the same channel of invocation:

I think it's worth considering changing to a more silent behaviour.

My suggestion:

• The bot should not give feedback for invalid command names.
  • Example: !poiints will not be given feedback by the bot.
• Invalid command arguments should be replied to with an error message in the same channel of invocation.
  • We don't actually have any such commands (except maybe the suffix-syntax command). I'm suggesting this for the future.
  • To illustrate this behaviour though, let's suppose we have !random command.
    • Suppose !random 10 is a command to dice roll from 1 to 10.
    • Suppose !random 9999999999999999999999999999999999 is an invalid command because the number is too big.
    • That invalid command is an example of such a command invocation that I think should be given feedback to the user.
• We should also fix the MD injection vulnerability with these error messages. (See the comments for a demo.)

Alternative ideas:

• Maybe some variation of using DMs?

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(This issue originates from the comments of #24)

[cubiquitous]

I just checked and if you write code like "a" !== "b" it will see as if is a command, so even normal code written could be interpreted by the bot. therefore I also think that we should change this behavior

[simshadows]

🤔

[simshadows]

Side-note: the error message is also vulnerable to MD injection

[cubiquitous]

just to add to the issue for documentation purposes, @doulovera pointed out that any message containing ! in the beginning will trigger the command, even if is in a codeblock.

Due to this, I'm in favor of @doulovera proposal of only triggering a command if is in the beginning of a message.