ServiceNow Flow Designer - Invalid property id error

Question

The error: invalid property id (Process Automation.65fea5d993050210f7db35918bba1034.InlineScript_assignment_groupa1fea5d9f5050210d8e77cda73f14762; line 10)

The Code: // Get the incident category var category = current.category;

// Define a map to store category-to-group
var assignmentMap = {
  "Hardware": "Hardware",
  "Software": "Software",
  "Network": "Network",
  "Inquiry/Help": "Help Desk",
  null: "Incident Management",
};

// Does the category exists in the map
var assignedGroup = assignmentMap[category];

// Assign the group to the incident if found
if (assignedGroup) {
  current.assignment_group = assignedGroup;
} else {

  gs.info ("no assignment for " +category);
}

// Update the incident record
current.update();

I am expecting that assignment groups get associated with categories at creation or update of records.