Error: array_map(): Argument #2 ($array) must be of type array, null given

• /srv/code/openfun.app/budgetdata/views/budget_proposal/unit_table_of_contents.php:18
• /srv/code/openfun.app/budgetdata/views/budget_proposal/unit_table_of_contents.php:18
• /srv/code/openfun.app/budgetdata/mini-engine.php:427
• /srv/code/openfun.app/budgetdata/views/budget_proposal/unit.php:13
• /srv/code/openfun.app/budgetdata/mini-engine.php:427
• /srv/code/openfun.app/budgetdata/mini-engine.php:458
• /srv/code/openfun.app/budgetdata/mini-engine.php:292
• /srv/code/openfun.app/budgetdata/mini-engine.php:254
• /srv/code/openfun.app/budgetdata/index.php:4