front: fix "invalid Date" errors

[emersion]

See individual commits.

Closes: https://github.com/OpenRailAssociation/osrd/issues/7836

[codecov-commenter]

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Codecov Report

Attention: Patch coverage is 0% with 8 lines in your changes missing coverage. Please review.

Project coverage is 28.53%. Comparing base (535a3db) to head (88cc92f). Report is 35 commits behind head on dev.

Files	Patch %	Lines
front/src/utils/date.ts	0.00%	8 Missing :warning:

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Additional details and impacted files

```diff @@ Coverage Diff @@ ## dev #7896 +/- ## ============================================ - Coverage 28.69% 28.53% -0.16% - Complexity 2058 2059 +1 ============================================ Files 1249 1249 Lines 154409 154183 -226 Branches 3040 3036 -4 ============================================ - Hits 44304 44001 -303 - Misses 108292 108372 +80 + Partials 1813 1810 -3 ``` | [Flag](https://app.codecov.io/gh/OpenRailAssociation/osrd/pull/7896/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=None) | Coverage Δ | | |---|---|---| | [core](https://app.codecov.io/gh/OpenRailAssociation/osrd/pull/7896/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=None) | `74.95% <ø> (-0.06%)` | :arrow_down: | | [editoast](https://app.codecov.io/gh/OpenRailAssociation/osrd/pull/7896/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=None) | `71.66% <ø> (-0.37%)` | :arrow_down: | | [front](https://app.codecov.io/gh/OpenRailAssociation/osrd/pull/7896/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=None) | `10.00% <0.00%> (-0.02%)` | :arrow_down: | | [gateway](https://app.codecov.io/gh/OpenRailAssociation/osrd/pull/7896/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=None) | `2.34% <ø> (-0.07%)` | :arrow_down: | | [railjson_generator](https://app.codecov.io/gh/OpenRailAssociation/osrd/pull/7896/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=None) | `87.49% <ø> (ø)` | | | [tests](https://app.codecov.io/gh/OpenRailAssociation/osrd/pull/7896/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=None) | `72.93% <ø> (ø)` | | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=None#carryforward-flags-in-the-pull-request-comment) to find out more.

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[theocrsb]

LGTM