New bug that never happen in previous version

[XJTLUmedia]

what the bug is:
werkzeug.routing.exceptions.BuildError: Could not build url for endpoint 'index'. Did you mean 'profile' instead?

Describe how to replicate the bug.

Running code from below, which is a guide showing in flask document quickstart

`from flask import Flask,url_for

app = Flask(__name__)

@app.route("/")
def hello_world():
    return "<p>Hello, World!</p>"

from markupsafe import escape

@app.route('/user/<username>')
def show_user_profile(username):
    # show the user profile for that user
    return f'User {escape(username)}'

@app.route('/post/<int:post_id>')
def show_post(post_id):
    # show the post with the given id, the id is an integer
    return f'Post {post_id}'

@app.route('/user/<username>')
def profile(username):
    return f'{username}\'s profile'

with app.test_request_context():
    print(url_for('index'))
    print(url_for('login'))
    print(url_for('login', next='/'))
    print(url_for('profile', username='John Doe'))`

Describe the expected behavior that should have happened but didn't.

No errors for these code for previous version of flask. So there should be no problem for this version also

Environment:

• Python version: 3.10.6
• Flask version: 2.2.2

[tachyondecay]

Your code is missing an index() view function. The quickstart’s version is:

@app.route('/')
def index():
    return 'index'

Without the above code, calling url_for('index') naturally results in a BuildError.