Once there is a non valid MultiJob Phase (i.e. with a Jub name that doesn't exists), the MultiJob Detailed Table (See Image) is missing.
In this case, I think that the plugin should do 1 of the following:
1. When a job is not valid, the save button should be disabled / error message will be displayed to the user after click on save (so it will not be saved in this way).
2. An error message should be displayed instead of the missing table.