Fix empty state for courses with no reviews

[codecov[bot]]

Codecov Report

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

Project coverage is 86.10%. Comparing base (066e036) to head (6fda1d1).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #584 +/- ## ======================================= Coverage 86.10% 86.10% ======================================= Files 45 45 Lines 6441 6441 ======================================= Hits 5546 5546 Misses 895 895 ```

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