MRE for Can not capture the child class of "Exception" in app.exception_handler globally

steps

1. git clone https://github.com/4tst/mre-exception-handler.git
2. python server.py
3. open ./frontend/index.html in browser and watch network tab in devtools

test 1

1. comment @app.exception_handler(ValueError)
2. refresh index.html and observe devtools, the api responses 200, but with CORS Error

test 2

1. uncomment @app.exception_handler(ValueError)
2. refresh index.html and observe devtools, the api responses as expected