fix(image): guard layer access during/after teardown

bec_widgets/widgets/plots/image/image_base.py

@@ -1036,6 +1036,8 @@ class ImageBase(PlotBase):
         """
 
         # FIXME: this should be made more general
+        if not self.layer_manager:
+            return False
         return self.layer_manager["main"].image.autorange
 
     @autorange.setter
@@ -1056,6 +1058,8 @@ class ImageBase(PlotBase):
             enabled(bool): Whether to enable autorange.
             sync(bool): Whether to synchronize the autorange state across all layers.
         """
+        if not self.layer_manager:
+            return
         for layer in self.layer_manager:
             if not layer.sync.autorange:
                 continue
@@ -1077,6 +1081,8 @@ class ImageBase(PlotBase):
             - "mean": Use the mean value of the image for autoranging.
 
         """
+        if not self.layer_manager:
+            return "mean"
         return self.layer_manager["main"].image.autorange_mode
 
     @autorange_mode.setter
@@ -1090,6 +1096,8 @@ class ImageBase(PlotBase):
         # for qt Designer
         if mode not in ["max", "mean"]:
             return
+        if not self.layer_manager:
+            return
         for layer in self.layer_manager:
             if not layer.sync.autorange_mode:
                 continue
@@ -1125,6 +1133,8 @@ class ImageBase(PlotBase):
         """
         Synchronize the autorange switch with the current autorange state and mode if changed from outside.
         """
+        if not self.layer_manager:
+            return
         action: SwitchableToolBarAction = self.toolbar.components.get_action("image_autorange")  # type: ignore
         with action.signal_blocker():
             action.set_default_action(f"{self.layer_manager['main'].image.autorange_mode}")
@@ -1133,7 +1143,7 @@ class ImageBase(PlotBase):
     def _sync_colorbar_levels(self):
         """Immediately propagate current levels to the active colorbar."""
 
-        if not self._color_bar:
+        if not self._color_bar or not self.layer_manager:
             return
 
         total_vrange = (0, 0)

tests/unit_tests/test_image_view_next_gen.py

@@ -1456,4 +1456,26 @@ def test_adjust_image_buffer_coerces_list_and_scalar(qtbot, mocked_client):
     buf = view.adjust_image_buffer(image, [1, 2, 3])  # python list
     assert buf.shape == (1, 3)
     buf = view.adjust_image_buffer(image, np.array(42.0))  # 0-d scalar
-    assert buf.shape[0] == 2
+    assert buf.shape[0] == 2
+
+
+##############################################
+# Teardown safety
+##############################################
+
+
+def test_layer_accessors_safe_after_teardown(qtbot, mocked_client):
+    """Once layer_manager is gone (post-cleanup), signal-driven accessors must
+    not raise. They used to subscript None or resurrect the 'main' layer."""
+    view = create_widget(qtbot, Image, client=mocked_client)
+    view.enable_full_colorbar = True
+    view.layer_manager = None  # simulate post-cleanup state
+
+    # None of these should raise:
+    assert view.autorange is False
+    assert view.autorange_mode == "mean"
+    view.toggle_autorange(True, "mean")
+    view._set_autorange(True)
+    view.autorange_mode = "max"
+    view._sync_autorange_switch()
+    view._sync_colorbar_levels()