BUG: fix the error when loading a non-cosmological Gizmo dataset

[jisuoqing]

Fix the error 'GizmoFieldInfo' object has no attribute 'nuclei_names' complained by Line 122

yt/yt/frontends/gizmo/fields.py

Lines 122 to 124 in bd6357e

	for species in self.nuclei_names:
	self.add_field(
	(ptype, f"{species}_nuclei_mass_density"),

when loading a non-cosmological Gizmo dataset.

[neutrinoceros]

Nice catch ! Shouldn't self.species_names be assigned in the else branch too ?

[neutrinoceros]

Shouldn't self.species_names be assigned in the else branch too ?

I can answer that myself: it's not needed, because this one is already set by FieldInfoContainer.__init__. nuclei_names on the other hand is a frontend-specific attribute.