How to remove Internal Server Error when running page in Flask?

Question

Flask

Hello. A 500 Internal Server Error occurs when navigating to the /search4 page. It seems that the module was created and imported according to the instructions from the book, but the error still exists.

from flask import Flask
from vsearch import search4letters

app = Flask(__name__)

@app.route('/')
def hello() -> str:
    return 'Hello world from Flask!'
@app.route('/search4')
def do_search() -> str:
    return str(search4letters('life, the universe, and everything', 'eiru,!'))

app.run()

Answer 1

logs

str(search4letters('life, the universe, and everything', 'eiru,!'))

check what is returned