Because of the way we're using in-channel replies - your original slash command is replaced by the output from slack - if you enter it wrong, you can't edit your last message by using the up arrow to make corrections.
A simple solution would be to include the original slash command in the error message to make it easier copy, paste, and modify. The slack API has also changed since this was originally written and there may be other, more effective ways to drive this interaction.
Because of the way we're using in-channel replies - your original slash command is replaced by the output from slack - if you enter it wrong, you can't edit your last message by using the up arrow to make corrections.
A simple solution would be to include the original slash command in the error message to make it easier copy, paste, and modify. The slack API has also changed since this was originally written and there may be other, more effective ways to drive this interaction.