fix: always return input for non-promoted scalars

src/awkward/operations/ak_to_layout.py

@@ -95,12 +95,13 @@ def maybe_merge_mappings(primary, secondary):
         return {**primary, **secondary}
 
 
-def _handle_as_scalar(obj, layout, *, scalar_policy):
+def _handle_as_scalar(obj, *, scalar_policy):
     assert scalar_policy in ("allow", "promote", "error")
 
     if scalar_policy == "allow":
-        return layout[0]
+        return obj
     elif scalar_policy == "promote":
+        layout = ak.operations.from_iter([obj], highlevel=False)
         return layout
     else:
         assert scalar_policy == "error"
@@ -110,8 +111,17 @@ def _handle_as_scalar(obj, layout, *, scalar_policy):
 
 
 def _handle_array_like(obj, layout, *, scalar_policy):
+    assert scalar_policy in ("allow", "promote", "error")
     if obj.ndim == 0:
-        return _handle_as_scalar(obj, layout, scalar_policy=scalar_policy)
+        if scalar_policy == "allow":
+            return obj
+        elif scalar_policy == "promote":
+            return layout
+        else:
+            assert scalar_policy == "error"
+            raise TypeError(
+                f"Encountered a scalar ({type(obj).__name__}), but scalars conversion/promotion is disabled"
+            )
     else:
         return layout
 
@@ -204,12 +214,10 @@ def _impl(
                 f"Encountered a scalar ({type(obj).__name__}), but scalars conversion/promotion is disabled"
             )
     elif isinstance(obj, (datetime, date, time, Number, bool)):
-        layout = ak.operations.from_iter([obj], highlevel=False)
-        return _handle_as_scalar(obj, layout, scalar_policy=scalar_policy)
+        return _handle_as_scalar(obj, scalar_policy=scalar_policy)
     elif obj is None:
         if allow_none:
-            layout = ak.operations.from_iter([obj], highlevel=False)
-            return _handle_as_scalar(obj, layout, scalar_policy=scalar_policy)
+            return _handle_as_scalar(obj, scalar_policy=scalar_policy)
         else:
             raise TypeError("Encountered None value, and `allow_none` is `False`")
     # Iterables