I am working on building an LWC component for a requirement. I would like to find a way to change/update the properties of an JavaScript Array that contains objects returned from Apex Controller. I tried below code, but there seems to be a javascript error. I tried many ways to change the properties of the object returned by Apex controller. But nothing worked. Code snippet & error details provided below. Can someone please help on this ?
 

public class FetchCPData {
    @AuraEnabled(cacheable=true)
    public static List<PRListWrapper> getPRList(String CPId) {
        List<PRListWrapper> prList = new List<PRListWrapper>();
        for(PR__C pr : [SELECT Id, Status__c, Value__c, (select Id, Name from Opportunities__r limit 1) FROM PR__C WHERE PC__c=:CPId]){
            PRListWrapper prw = new PRListWrapper();
            prw.PRRecord = pr;
            if(!pr.Opportunities__r.isEmpty()) 
            {
                prw.disable = true;
            }else {
                prw.disable = false;
            }
            prList.add(prw);
        }
        return prList;
    }
    public class PRListWrapper{
        @AuraEnabled public Boolean disable;
        @AuraEnabled public PR__C PRRecord;
    }
}

import { LightningElement, api, wire, track} from 'lwc';
import getPRList from '@salesforce/apex/FetchCPData.getPRList';
const actions = [
    { label: 'Delete', name: 'Delete' }
];
const columns = [
    { label: 'Status', fieldName: 'status', editable:'true', type: 'text' },
    { label: 'Bid Value', fieldName: 'value', editable:'true', type: 'currency', typeAttributes: { currencyCode: 'USD'}},
    {
        type: 'action',
        typeAttributes: { rowActions: actions }
    }
]
export default class ShowDataInTable extends LightningElement {
    @api recId;
    @track error;
    @track recSize;
    @track data = [];
    @track columns = columns;
    @wire(getPRList, { CPId : '$recId' }) 
    projectRolesFn ({error , data}){
        if(data){
            const lostFilter = data.filter(element => {
                return element.PRRecord.Status__c!=='Lost';
            });
            this.data = lostFilter.map(element => {
                alert(element.PRRecord.Status__c); //This is fetching data as expected
                alert(element.PRRecord.Value__c);  //This is fetching data as expected
                element.status = element.PRRecord.Status__c; //JavaScript error at this point(error given below)
                element.value = element.PRRecord.Value__c;
                return element;
            });      
            this.recSize = this.data.length;
            this.error = undefined;           
        } else if(error){
            this.error = error;
            this.data = undefined;
        }
    }
}

JavaScript Error:
aura_proddebug.js:43117 Error: Invalid mutation: Cannot set "status" on "[object Object]". "[object Object]" is read-only. at ReadOnlyHandler.set (aura_proddebug.js:1100) at eval (showBiddersInTable.js:81) at Array.map () at ShowBiddersInTable.projectRolesFn (showBiddersInTable.js:79) at WireEventTarget.dispatchEvent (aura_proddebug.js:8329) at Object.next (lds.js:1157) at Subscription.next (lds.js:202) at FilterOnSubscribeBehaviorSubject._nextWithErrorHandling (lds.js:272) at eval (lds.js:304) at Set.forEach ()