Bulk execution for non-executable Tests in TestExecution throws an unhandled exception

To reproduce this error:
1. Ensure that the Test (Template/source) is in the status 'TODO'.
=> Note: A Test (template/source) in a status other than 'toDO' works fine (e.g. WORKING).
2. Open a TestExecution and add the Test to the Tests pnel. (The status appears as TODO).
=> Note: The Test 'instance' (on the Tests panel in TestExecution) displays the warning message: 'This Test is in a non-executable status'.
3. Select the checkbox on the Test instance (which has the status TODO).
4. Select a highlighted status (e.g. 'FAIL', 'PASSED', etc.) in the inline dropdown menue (...) (top left of the Tests panel).
5. An error (exception) is displayed to the User.

Expected result:
No error/exception is displayed to the User.