NPE when trying to add changes to a CR requesting deletion of same page

Reproduction steps:

• Create a CR requesting deletion of a specific page (e.g. Main.WebHome)
• Start edition of the same page
• Save as change request
• In the modal chose to add changes to the existing change request
• Select the CR created at first step

Expected result:

• an error should be displayed because the change cannot be merged (known limitation)

Obtained result:

• a NPE appears in console