Properly Rethrow Get-Karma errors in Show-Karma

[vexx32]

PR Summary

Before this PR, Show-Karma did not properly catch and rethrow errors from Get-Karma, causing the user to receive errors from Get-Karma and Show-MeditationPrompt when calling Show-Karma, which is unnecessary and confusing.

Context

One error that clearly comes from Show-Karma rather than two errors from the internal functions it's calling is a much better UX.

Changes

• Properly rethrow Get-Karma errors from Show-Karma.
• Update Get-Karma error messages to be more useful.

Checklist

• Pull Request has a meaningful title.
• Summarised changes.
• Pull Request is ready to merge & is not WIP.
• Added tests / only testable interactively.
  • Make sure you add a new test if old tests do not effectively test the code changed.
• Added documentation / opened issue to track adding documentation at a later date.