Fix error finding modules in MultiModuleConstant

src/cal_tools/calcat_interface2.py

@@ -340,7 +340,7 @@ class MultiModuleConstant(Mapping):
         for m in self.module_details:
             names = (m["module_number"], m["virtual_device_name"], m["physical_name"])
             if key in names and m["karabo_da"] in self.constants:
-                candidate_kdas.add([m["karabo_da"]])
+                candidate_kdas.add(m["karabo_da"])
 
         if not candidate_kdas:
             raise KeyError(key)