I'm trying to send a post request to a new route in flask/react.js, what am I doing wrong?

Question

I am trying to send the contents of a flashcard to a backend route http://127.0.0.1:5000/post onClick and it works when I send the data to webhook.site but when I change it to http://127.0.0.1:5000/post I get the error " question = data['question' TypeError: 'NoneType' object is not subscriptable ". Here is the code for the fetch request: async function postData() {

try {

    let result = await fetch('http://127.0.0.1:5000/post', {
        method: 'POST',
        mode: 'no-cors',
        headers: {
            'Accept': 'application/json',
            'Content-Type': 'application/json',

        },
        body: JSON.stringify({
            key: `${Date.now()}`,
            question: flashcard.question,
            answer: flashcard.answer,
            options: flashcard.options
        })
    });
} catch(e) {
    console.log(e)
}
}

and here is the code for the backend route in flask:

@app.route('/post', methods=['GET', 'POST'])
def post():
data = request.get_json()

question = data['question']
answer = data['answer']
options = data['options']
key = data['key']

return jsonify({'question' : question, 'answer' : answer, 'options' : options, 'key' : key})


if __name__ == "__main__":
app.run(debug=True)

I get that the error is stating that "data" has no value which I assume means it's not recieving the JSON objects that I'm posting. It's weird because it works perfectly when I use a webhook.site url. can anyone help? thanks for your time!