safer check for zapped classes when opening element attributes page. F…

…ixes #167

src/containers/EditAttributes.js

@@ -98,6 +98,7 @@ const mapStateToProps = (state, ownProps) => {
         // but if its module is selected, it may have been zapped. So include it.
         // BUT do not restore it if it's been explicitly deleted by the user.
         if (state.odd.localsource.json.modules.filter(m => m.ident === localClass.module)[0]
+          && state.odd.customization.json.classes._deleted
           && !state.odd.customization.json.classes._deleted.includes(className)) {
           return _computeAtts(localClass)
         }