Test for spectra errors

```Python
def test_check_spectrum_wave_units_errors(t_spectrum):
t_spectrum.spectral_axis = t_spectrum.spectral_axis * u.m # Set incorrect units
with pytest.raises(AstroDBError) as error_message:
check_spectrum_units(t_spectrum, raise_error=True)

assert "Unable to convert spectral axis to microns" in str(error_message)

def test_check_spectrum_flux_units_errors(t_spectrum):
```

Locate check_spectrum_units and the existing tests that cover spectral-axis unit errors. Use the shown wave-unit test as the starting point, determine the corresponding flux-unit error case, and run the relevant pytest tests to confirm both error paths.

Written by the indexing model from the issue text.