Convert field_info into a property so it can be created on first access.

Author: brittonsmith

yt/data_objects/static_output.py

@@ -171,6 +171,7 @@ class Dataset(abc.ABC):
     field_units: dict[AnyFieldKey, Unit] | None = None
     derived_field_list = requires_index("derived_field_list")
     fields = requires_index("fields")
+    _field_info = None
     conversion_factors: dict[str, float] | None = None
     # _instantiated represents an instantiation time (since Epoch)
     # the default is a place holder sentinel, falsy value
@@ -654,7 +655,18 @@ def print_stats(self):
     def field_list(self):
         return self.index.field_list
 
+    @property
+    def field_info(self):
+        if self._field_info is None:
+            self.create_field_info()
+        return self._field_info
+
+    @field_info.setter
+    def field_info(self, value):
+        self._field_info = value
+
     def create_field_info(self):
+        self.index
         self.field_dependencies = {}
         self.derived_field_list = []
         self.filtered_particle_types = []