Description:
This commit addresses an issue where certain properties (files, keyword, messages, nosy, superseder) do not have assigned values, resulting in null values that cannot be grouped. To prevent potential errors, a validation check has been added to ensure that these properties are not selected. Additionally, a comment has been included in the code to provide clarity on the issue and the fix applied.
Title: Fix handling of unassigned properties
Description: This commit addresses an issue where certain properties (files, keyword, messages, nosy, superseder) do not have assigned values, resulting in null values that cannot be grouped. To prevent potential errors, a validation check has been added to ensure that these properties are not selected. Additionally, a comment has been included in the code to provide clarity on the issue and the fix applied.