diff --git a/pyproject.toml b/pyproject.toml
index d832213792..7d7f6719fc 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -111,7 +111,6 @@ no-matching-overload = "ignore"
 not-subscriptable = "ignore"
 unsupported-dynamic-base = "ignore"
 unsupported-operator = "ignore"
-type-assertion-failure = "ignore"
 
 [tool.ty.environment]
 extra-paths = [
diff --git a/requirements-tools.txt b/requirements-tools.txt
index 33a2505707..8f7aa4f792 100644
--- a/requirements-tools.txt
+++ b/requirements-tools.txt
@@ -1,5 +1,5 @@
 black==26.3.1
 ruff==0.15.12
 poethepoet
-ty==0.0.59
+ty==0.0.61
 gersemi==0.26.1
diff --git a/src/bonsai/bonsai/tool/pset.py b/src/bonsai/bonsai/tool/pset.py
index aa72a85e6f..47d5155eee 100644
--- a/src/bonsai/bonsai/tool/pset.py
+++ b/src/bonsai/bonsai/tool/pset.py
@@ -124,6 +124,9 @@ class Pset(bonsai.core.tool.Pset):
             return bpy.context.scene.GroupPsetProperties
         elif obj_type == "Zone":
             return bpy.context.scene.ZonePsetProperties
+        elif obj_type == "Cost":
+            # No psets for cost items currently.
+            assert False, obj_type
         assert_never(obj_type)
 
     @classmethod