TypeScript Error: The Object prototype must be an Object or null, it cannot be undefined

Just recently, I delved into TypeScript and attempted to convert a JavaScript code to TypeScript while incorporating more object-oriented features. However, I encountered an issue when trying to execute it with cmd using the ns-node command.

private username:string;
           ^
TypeError: Object prototype may only be an Object or null: undefined

This error seemed puzzling, so I resorted to searching online for solutions. Despite trying various suggestions from different sources, none of them resolved the issue.

Here's a snippet of my code:

import { Entity } from './Entity';
import { Bullet } from './Bullet';

import * as fs from "fs";
export class Player extends Entity{

private username:string;
protected pressingRight:boolean ;
protected pressingLeft:boolean ;
...
}

Can anyone pinpoint what might be causing this problem? Your assistance is greatly appreciated.

EDIT:

    import {Point} from "./Point";
    import {Bullet} from "./Bullet";
import {Player} from "./Player";
export class Entity{

protected x:number;
protected y:number;
protected spdX:number = 0;
protected spdY:number = 0;
protected id:number;
protected map:string;


protected static initPack = {player:[],bullet:[]};
protected static removePack = {player:[],bullet:[]};

 constructor(x:number,y:number,id:number,map:string){
    this.x = x;
    this.y=y;
    this.id=id;
    this.map=map;
 }
...}

Additionally, here is the content of Bullet.ts :

    import {Entity} from './Entity';
import {Player} from './Player';
export class Bullet extends Entity{

private angle:number;
private parentID:number;
private timer:number = 0;
private toRemove:boolean=false;

public static list={};

constructor(x:number,y:number,map:string,parentId:number,angle:number,id:number){
    super(x,y,id,map);
    this.angle = angle;
    this.spdX= Math.cos(angle/180*Math.PI) * 10;
    this.spdY= Math.sin(angle/180*Math.PI) * 10;
    this.parentID = parentId;

    Bullet.list[this.id] = self;
    Bullet.initPack.bullet.push(this.getInitPack());
}

Answer №1

Having cyclic imports can cause issues in your code. When ts-node encounters an import of a file that is still in the process of loading, it will continue past that import even though the imported file is not fully loaded yet. This is why you may encounter situations where Entity is undefined after importing it from './Entity'.

To avoid this problem, consider rearranging your imports. If 'Entity.ts' does not immediately require access to the 'Player' class, try moving the

import { Player } from './Player';
line to the bottom of 'Entity.ts'.

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