User Story: Error messages

[MineKecks]

As a user I want to get an error message when board can't be loaded in order to know when something went wrong.

• [ ] find all implemented errors
• [ ] sort out which to show to user
• [ ] implent
• [ ] other errors we want to show to user?

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Housekeeping

• [ ] model updated
• [ ] tests added
  • [ ] tests green
• [ ] coding style checked
• [ ] doku checked