JavaScript: Object reference not set to an instance of an object

The script  was created using Rawish Kumars example.  It fails with the general error "Internal Server Error."  From debugger mode, "req:XMLHttpRequest: response" indicates the error is "Object reference not set to an instance of an object".

**** Begin of script

function VPNApplicable_Opt() {
debugger;
    
    var fieldValueToCopy  = Xrm.Page.getAttribute("new_2vpnapplicable").getValue();
    var lookupObj = Xrm.Page.getAttribute("objectid").getValue();
    var newid = lookupObj[0].id.slice(1, -1); // you will get perfect id like "EDCJDKDJDKJDJDKJDJKD" here.

    var req = new XMLHttpRequest();
    /*
    var primaryProjectId;
    EntityReference  primaryProjectId = new EntityReference ("msdyn_projects", newid);
    console.log(primaryProjectId);
    
    queueitem["primaryProjectId"] = primaryProjectId;    
    */
    req.open("PATCH", Xrm.Page.context.getClientUrl() + "/api/data/v9.0/msdyn_projects(" + newid + ")?$select=new_2vpnapplicable$expand=msdyn_project_QueueItems($select=objectid)", true);
    /*
    var url = Xrm.Page.context.getClientUrl() + "/api/data/v9.0/msdyn_projects(" + newid + ")?$select=new_2vpnapplicable, projectid$expand=msdyn_project_QueueItems($select=objectid)";
    console.log(url);
    req.open("GET", url, true);
    */
    req.setRequestHeader("OData-MaxVersion", "4.0");
    req.setRequestHeader("OData-Version", "4.0");
    req.setRequestHeader("Accept", "application/json");
    req.setRequestHeader("Content-Type", "application/json; charset=utf-8");
    req.setRequestHeader("Prefer", "odata.include-annotations=\"*\"");
    req.onreadystatechange = function () {
        if (this.readyState === 4) {
            req.onreadystatechange = null;
            if (this.status === 200) {
                var result = JSON.parse(this.response); // you will get the retrieved value in object we stored in result var.

                var retrivedvalue = result.new_2vpnapplicable; //get the id of the field
                //var retrivedformatedvalue = result["new_2vpnapplicable@OData.Community.Display.V1.FormattedValue"]; //get the formatted name of the field
                if (retrivedvalue != null) {
                    var value = new Array();
                    value[0] = new Object();
                    value[0].id = retrivedvalue;
                    //value[0].name = retrivedformatedvalue;
                    value[0].entityType = "msdyn_projects";
                    // console.log(value[0]);
                    Xrm.Page.get

Attribute("new_2vpnapplicable").setValue(fieldValueToCopy); //set the lookup value finally
                } else
                    alert("some textt!!!!!!") // optional
            } else {
                Xrm.Utility.alertDialog(this.statusText);
            }
        }
    };
    req.send();
}

****** End of script

I tested the URL and got the desired results:

*** URL results

@odata.context "xxxxxxxxxxxxxxxx.crm.dynamics.com/.../v9.0$metadata#msdyn_projects(new_2vpnapplicable)/$entity"

@odata.etag "W/\"17715491\""

new_2vpnapplicable 100000001

msdyn_projectid "089cc620-95c8-e711-8119-e0071b6a5d41"

**** end link