This means you have entered a sprite which isn’t a sprite file, this might be because you’ve typed it in wrong or the sprite does not exist, for a list of sprites, see the above link. (this only happens if you are using Demirrmon’s textbox generator)
This means you have entered an expression which the sprites doesn’t have, you might have made a typo, bear in mind just because one sprite has an expression doesn’t mean all the others will have the same expression.
The textbox generator uses the font ‘Determination’, which is a variant of the 8-bit operator font which doesn’t have alot of support for characters, so this is a technical limitation that it can’t render all characters that may get thrown at it.
This is usually caused by one of two things, API downtime or a permission denied error. The bot has two commands to help you resolve this, you can use the ‘debug’ command to see if the bot is missing any permissions, and you can use the ‘ping’ command to see if the APIs the bot uses are running, if the APIs are down this can usually only be fixed by waiting for the API to come back up.
The bot also may not have permissions to respond in the current channel, if it doesn’t it will try and dm you, but if it can’t the bot can’t do anything to let you know.