Simple navCtrl.pop() not working anymore

Ionic Framework ionic-v3
1

This code below was working perfectly yesterday. All I am trying to do is to simply go back to the previous page after a successful login.

if(env.navParams.get('param1')=='from-order-page'){
    console.log("----------------------------------");
    nav.pop('OrderPage');
}

but strangely stops today. I have done some plugin installation and probably that may have affected some aspects of my code. This is the error below.

[22:46:03]  typescript: src/pages/login/login.ts, line: 64 
Type '"OrderPage"' has no properties in common with type 'NavOptions'. 

L63:    console.log("----------------------------------");
L64:    nav.pop('OrderPage');
L65:  }else{...

Ionic Information is below

cli packages: (/path/appname/node_modules)

@ionic/cli-utils  : 1.19.0
ionic (Ionic CLI) : 3.19.0

global packages:

cordova (Cordova CLI) : 7.1.0

local packages:

@ionic/app-scripts : 3.1.4
Cordova Platforms  : android 6.3.0 ios 4.5.4
Ionic Framework    : ionic-angular 3.5.3

System:

Android SDK Tools : 26.1.1
Node              : v8.1.3
npm               : 5.5.1 
OS                : Linux 4.4

Misc:

backend : pro
2

I believe it should just be nav.pop();, particularly as based on the error message it’s expecting you to pass NavOptions to it and not a string.