Fix return of 0-length tibbles for TEOW

[codecov[bot]]

Codecov Report

Attention: 3 lines in your changes are missing coverage. Please review.

Comparison is base (59a4c93) 73.36% compared to head (a48f71a) 73.31%.

:exclamation: Current head a48f71a differs from pull request most recent head 2a8f8fd. Consider uploading reports for the commit 2a8f8fd to get more accurate results

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #199 +/- ## ========================================== - Coverage 73.36% 73.31% -0.05% ========================================== Files 43 43 Lines 1817 1825 +8 ========================================== + Hits 1333 1338 +5 - Misses 484 487 +3 ``` | [Files](https://app.codecov.io/gh/mapme-initiative/mapme.biodiversity/pull/199?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=mapme-initiative) | Coverage Δ | | |---|---|---| | [R/calc\_biome.R](https://app.codecov.io/gh/mapme-initiative/mapme.biodiversity/pull/199?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=mapme-initiative#diff-Ui9jYWxjX2Jpb21lLlI=) | `95.23% <100.00%> (+0.50%)` | :arrow_up: | | [R/calc\_ecoregion.R](https://app.codecov.io/gh/mapme-initiative/mapme.biodiversity/pull/199?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=mapme-initiative#diff-Ui9jYWxjX2Vjb3JlZ2lvbi5S) | `95.74% <75.00%> (-2.04%)` | :arrow_down: | | [R/calc\_indicators.R](https://app.codecov.io/gh/mapme-initiative/mapme.biodiversity/pull/199?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=mapme-initiative#diff-Ui9jYWxjX2luZGljYXRvcnMuUg==) | `70.90% <50.00%> (-0.79%)` | :arrow_down: |

:umbrella: View full report in Codecov by Sentry.
:loudspeaker: Have feedback on the report? Share it here.