avoid touching shape too much for purelist_depth, minmax_depth, and b…

…ranch_depth using inner_shape property

src/awkward/contents/numpyarray.py

@@ -175,7 +175,11 @@ def shape(self) -> tuple[ShapeItem, ...]:
 
     @property
     def inner_shape(self) -> tuple[ShapeItem, ...]:
-        return self._data.shape[1:]
+        if hasattr(self._data, "inner_shape"):
+            inner_shape = self._data.inner_shape
+        else:
+            inner_shape = self._data.shape[1:]
+        return inner_shape
 
     @property
     def strides(self) -> tuple[ShapeItem, ...]:
@@ -189,14 +193,9 @@ def _raw(self, nplike=None):
         return to_nplike(self.data, nplike, from_nplike=self._backend.nplike)
 
     def _form_with_key(self, getkey: Callable[[Content], str | None]) -> NumpyForm:
-        if hasattr(self._data, "inner_shape"):
-            inner_shape = self._data.inner_shape
-        else:
-            inner_shape = self._data.shape[1:]
-
         return self.form_cls(
             ak.types.numpytype.dtype_to_primitive(self._data.dtype),
-            inner_shape,
+            self.inner_shape,
             parameters=self._parameters,
             form_key=getkey(self),
         )