From d35ca864091c5dc6608d9e712348a2bc0faf7d50 Mon Sep 17 00:00:00 2001
From: Jammy2211 <JNightingale2211@gmail.com>
Date: Thu, 30 Jul 2026 20:17:17 +0100
Subject: [PATCH] fix: Optional[None] used as default value in tracer +
 max_separation

Optional[None] evaluates to NoneType, a truthy class object, so these
defaults silently passed `is not None` guards: the tracer's early-exit
block ran on every default call (comparing plane_index == NoneType, always
False) and SourceMaxSeparation's default only worked because
np.isclose(NoneType, z) raises the TypeError the except clause catches.
A real None preserves behavior at all three sites.

Closes #674

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
---
 autolens/lens/tracer.py          | 2 +-
 autolens/lens/tracer_util.py     | 2 +-
 autolens/point/max_separation.py | 2 +-
 3 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/autolens/lens/tracer.py b/autolens/lens/tracer.py
index b4cf929d6..e1b6811d9 100644
--- a/autolens/lens/tracer.py
+++ b/autolens/lens/tracer.py
@@ -247,7 +247,7 @@ def total_planes(self) -> int:
 
     @aa.decorators.to_grid
     def traced_grid_2d_list_from(
-        self, grid: aa.type.Grid2DLike, xp=np, plane_index_limit: int = Optional[None]
+        self, grid: aa.type.Grid2DLike, xp=np, plane_index_limit: Optional[int] = None
     ) -> List[aa.type.Grid2DLike]:
         """
         Returns a ray-traced grid of 2D Cartesian (y,x) coordinates which accounts for multi-plane ray-tracing.
diff --git a/autolens/lens/tracer_util.py b/autolens/lens/tracer_util.py
index fb3b24c22..9b9186fed 100644
--- a/autolens/lens/tracer_util.py
+++ b/autolens/lens/tracer_util.py
@@ -175,7 +175,7 @@ def traced_grid_2d_list_from(
     planes: List[List[ag.Galaxy]],
     grid: aa.type.Grid2DLike,
     cosmology: ag.cosmo.LensingCosmology = None,
-    plane_index_limit: int = Optional[None],
+    plane_index_limit: Optional[int] = None,
     xp=np,
 ):
     """
diff --git a/autolens/point/max_separation.py b/autolens/point/max_separation.py
index 411771014..aa7f22639 100644
--- a/autolens/point/max_separation.py
+++ b/autolens/point/max_separation.py
@@ -24,7 +24,7 @@ def __init__(
         data: aa.Grid2DIrregular,
         noise_map: Optional[aa.ArrayIrregular],
         tracer: Tracer,
-        plane_redshift: float = Optional[None],
+        plane_redshift: Optional[float] = None,
         xp=np,
     ):
         """