I can't get data from nest.js

I'm trying to get data from nest.js with vue.js. I getting this error:

Uncaught (in promise) TypeError: relativeURL.replace is not a function

Codes :

Api.js(vuejs)

import axios from "axios";

export default () => {
  return axios.create({
    baseURL: `http://localhost:5000`
  });
}

Backend-connection.js(vuejs)

import Api from './Api'

export default {
  getBasic(){
            return Api().post({
                headers : {
                    'Access-Control-Allow-Origin' : `*`,
            }
            });
    }
}

app.controller.ts (nestjs)

import { Controller, Get, Post } from '@nestjs/common';
import { AppService } from './app.service';

@Controller()
export class AppController {
  constructor(private readonly appService: AppService) {}

  @Get()
  get(): string {
    return this.appService.getStarted();
  }

  @Post('/')
  getPosts(): string {
    return this.appService.getStarted();
  }
}