Unable to update JSON object in LWC throwing :1 Uncaught (in promise) error

I have a wire function where i am getting data from apex

get userAddressBookData() {
    var selectedUserListBeforeApexCall = this.selectedAddressList;
    console.log('selectedUserListBeforeApexCall---', JSON.stringify(selectedUserListBeforeApexCall))
    for (var i = 0; i < this.selectedAddressList.length; i++) {
        let selectedShippingMethodId = this.selectedAddressList[i].selectedShippingMethodId;
        let selectedShippingMethod = this.shippingMethodListData.find(
            shippingmethod => shippingmethod.Id === selectedShippingMethodId
        );
        console.log('selectedShippingMethod---', JSON.stringify(selectedShippingMethod))
        if (selectedShippingMethod && selectedShippingMethod.ApprovalRequired__c) {
            // let approvalRequired  = this.selectedAddressList[i].isApprovalRequiredForShippingMethod;
            // approvalRequired = true;
            // console.log('here in')
            // this.selectedAddressList[i].isApprovalRequiredForShippingMethod = approvalRequired;
            // console.log('this.selectedAddressList[i].isApprovalRequiredForShippingMethod---',JSON.stringify(this.selectedAddressList[i].isApprovalRequiredForShippingMethod))

            this.selectedAddressList[i] = {
                ...this.selectedAddressList[i], // Spread operator to copy the existing object
                isApprovalRequiredForShippingMethod: true // Update the specific property
            };

        }
    }
}

based on some condition I am getting data but I am unable to update it it says uncaught in promise

please somebody help me as I am new to LWC this is the HTML code

 <template if:true={selectedList.isApprovalRequiredForShippingMethod}>
     <b style="color: #d12424;font-size:12px">The selected shipping method
 requires approval. This order will be submitted for shipping method approval.</b>
 </template>

this is the main template

<template for:each={selectedAddressList} for:item="selectedList">

this is the JSON data

[
    {
        "isApprovalRequiredForShippingMethod": false,
        "isCheckboxClicked": true,
        "quantity": 0,
        "selectedAddress": {
            "Id": "a08DF00000GZqVeYAL",
            "Name": "AB-00000",
            "City__c": "Travenieer",
            "Destination_Name__c": "ALex-Travenieer",
            "Shipto_Company__c": "Folio",
            "Shipto_Name__c": "ALex",
            "State__c": "a05DF000007R2kYYAS",
            "Address__c": "221b Bakers Street",
            "Active__c": true,
            "State__r": {
                "State_Name__c": "Florida",
                "Country__c": "a04DF00000DyUUyYAN",
                "Id": "a05DF000007R2kYYAS",
                "Country__r": {
                    "Country_Code__c": "US",
                    "Country_Name__c": "United States",
                    "Id": "a04DF00000DyUUyYAN"
                }
            }
        },
        "selectedShippingMethod": {},
        "selectedShippingMethodId": "a06DF00000FkZOUYA3"
    },
    {
        "isApprovalRequiredForShippingMethod": false,
        "isCheckboxClicked": true,
        "quantity": 0,
        "selectedAddress": {
            "Id": "a08DF00000GZt3eYAD",
            "Name": "AB-00001",
            "City__c": "Culver City",
            "Destination_Name__c": "Jonathan Boulangeat-Culver City",
            "Shipto_Company__c": "Folio Fine Wine Company",
            "Shipto_Name__c": "Jonathan Boulangeat",
            "State__c": "a05DF000007R2kYYAS",
            "Address__c": "5632 Canterbury Drive",
            "Active__c": true,
            "State__r": {
                "State_Name__c": "Florida",
                "Country__c": "a04DF00000DyUUyYAN",
                "Id": "a05DF000007R2kYYAS",
                "Country__r": {
                    "Country_Code__c": "US",
                    "Country_Name__c": "United States",
                    "Id": "a04DF00000DyUUyYAN"
                }
            }
        },
        "selectedShippingMethod": {},
        "selectedShippingMethodId": "a06DF00000FkZOUYA3"
    }
]