Axios not passing Content-Type header

Question

I'm running an Odoo instance in the backend, and I created a custom module that exposes a web controller as follows:

Web Controller

# -*- coding: utf-8 -*-
from odoo import http
import odoo
from odoo.http import Response, request
from werkzeug import wrappers
import json


class VueWebServices(http.Controller):
    @http.route('/vuews/msg/', auth='none', type='json', methods=['POST', 'GET', 'OPTIONS'], csrf=False)
    def answermsg(self, **post):
        product_ids = request.env['product.product'].sudo().search([])
        dict = {}
        r = request
        d = request.httprequest.data
        dv = http.request.params
        for k in product_ids:
            tuple = {}
            tuple.update({"name":k['name']})
            tuple.update({"id": k['id']})
            dict.update(tuple)
        return json.dumps(dict)

In order to allow cors, I'm also proxying odoo through Nginx. Here's what nginx.conf looks like:

nginx.conf

upstream odoo {
        server 127.0.0.1:8069;
    }
    server {
        listen  443 default;
        server_name localhost;
        root    c:/nginx/html;
        index   index.html index.htm;

        access_log c:/nginx/logs/odoo.access.log;
        error_log c:/nginx/logs/odoo.error.log;

        proxy_buffers 16 64k;
        proxy_buffer_size 128k;

        location / {
            proxy_pass  http://odoo;
            proxy_next_upstream error timeout invalid_header http_500 http_502 http_503 http_504;
            proxy_redirect off;

            proxy_set_header    Host            $host:$server_port;
            proxy_set_header    X-Real-IP       $remote_addr;
            proxy_set_header    X-Forwarded-For $proxy_add_x_forwarded_for;
            proxy_set_header    X-Forwarded-Proto https;

            add_header    'Access-Control-Allow-Origin' '*' always;
            add_header    'Access-Control-Allow-Methods' 'GET, POST, OPTIONS' always;
            add_header    'Access-Control-Allow-Headers' 'Origin, X-Requested-With, Content-Type, Accept' always;
            add_header    'Access-Control-Request-Headers' 'Content-Type' always;
            add_header    'Access-Control-Allow-Credentials' 'true' always;
        }

        location ~* /web/static/ {
            proxy_cache_valid 200 60m;
            proxy_buffering on;
            expires 864000;
            proxy_pass http://odoo;
        }


    }

When I try to access the route through postman, it works as expected. But when I try to access it through axios, I get 400 BAD REQUEST. In the odoo console, it throws me this: Function declared as capable of handling request of type 'json' but called with a request of type 'http'

Here's how my Vue JS app queries the controller:

axios({
      method: "POST",
      headers: {
        "Content-Type": "application/json",
        "Cache-Control": "no-cache",
      },
      data: {
        "message": "Hello World"
      },
      url: "http://localhost:443/vuews/msg"
    });

I'm clearly passing the content-type : 'application/json' header, so what's wrong?