Flask restful:JSONDecodeError

我想学习Flask构建后端服务，但我遇到了一个错误，我无法摆脱它

服务器：

    from flask import Flask
    from flask_restful import Resource, Api
    from flask_sqlalchemy import SQLAlchemy
    from flask_marshmallow import Marshmallow

    app = Flask(__name__)
    api = Api(app)
    app.config['SQLALCHEMY_DATABASE_URI'] = 'sqlite:///test.db'
    db = SQLAlchemy(app)
    ma = Marshmallow(app)
    
    class Post(db.Model):
        id = db.Column(db.Integer, primary_key=True)
        title = db.Column(db.String(50))
        content = db.Column(db.String(255))
    
        def __repr__(self):
            return '<Post %s>' % self.title
    
    class PostSchema(ma.Schema):
        class Meta:
            fields = ("id", "title", "content")
            model = Post
    
    post_schema = PostSchema()
    posts_schema = PostSchema(many=True)
    
    class PostListResource(Resource):
        def get(self):
            posts = Post.query.all()
            return posts_schema.dump(posts)
    
    api.add_resource(PostListResource, '/posts')
    
    
    if __name__ == '__main__':
        app.run(debug=True)

这给了我：

从None引发JSONDecodeError（“预期值”，s，err.value） json.decoder.JSONDecodeError:预期值：第1行第1列（字符 0）

我该怎么办

import requests

BASE = "http://127.0.0.1:5000/"

response_of_get = requests.get(BASE + "posts")
print(response_of_get.json())