[BUG] Some outputs fail to work

In MUSE 1.3.3, I get the following error when using the `emission_costs`, `fuel_costs` and `capital_costs` outputs:

  File "...venv\Lib\site-packages\xarray\core\indexes.py", line 791, in sel

    raise KeyError(

    ...<2 lines>...

    ) from e

KeyError: "not all values found in index 'year'. Try setting the 'method' keyword argument (example: method='nearest')."

Additionally, the `LCOE` and `AEC` outputs produce the following:

  File "...venv\Lib\site-packages\xarray\core\common.py", line 302, in __getattr__

    raise AttributeError(

        f"{type(self).__name__!r} object has no attribute {name!r}"

    )

AttributeError: 'Dataset' object has no attribute 'enduse'

It seems to be related to #421, but these errors did not appear in MUSE 1.3.2