fix(window): prevent SegmentationFault

Author: abrichr

openadapt/window/_macos.py

@@ -143,7 +143,8 @@ def deepconvert_objc(object):
         value = dict(object)
         for k, v in value.items():
             value[k] = deepconvert_objc(v)
-    value = atomacos._converter.Converter().convert_value(value)
+    if value:
+        value = atomacos._converter.Converter().convert_value(value)
     return value