Describe the bug

When a command is on cooldown, koala says there is an unexpected error even though the reason is known

To Reproduce

Numbered steps to reproduce the behavior:

1. k!enableExt ColourRole
2. Give yourself a role with customColour allowed
3. k!customColour 52E91E
4. k!customColour 52E91E immediately after
5. See error

Expected behaviour

The cooldown error should be shown without the 'unexpected error' message

Screenshots

N/A

Additional context

N/A