fix(migration_status): fix Twig error on migration_status page

[MyvTsv]

• I have performed a self-review of my code.
• I have added tests (when available) that prove my fix is effective or that my feature works.
• This change requires a documentation update.

Description

Strengthened verification of the presence of the genericobject asset in the customassets table to avoid a Twig error when the key is not defined.

Screenshots (if appropriate):

[Rom1-B]

Please update CHANGELOG