Throw an error when saving domains

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 94.85%. Comparing base (9cbf0b3) to head (e82c868).

:exclamation: Current head e82c868 differs from pull request most recent head 68c6451

Please upload reports for the commit 68c6451 to get more accurate results.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #82 +/- ## ======================================= Coverage 94.84% 94.85% ======================================= Files 17 17 Lines 1067 1068 +1 ======================================= + Hits 1012 1013 +1 Misses 55 55 ```

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