send_file from flask pymongo not working for images

Question

I'm trying to make a simple example for sending and receiving files to a mongo db and I can see the images being uploaded correctly to mongodb using mongodbcompass, but I get a type error when I try to retrieve the file and show it. Any help is greatly appreciated!

from flask import Flask, request, url_for
from flask_pymongo import PyMongo
import urllib

app = Flask(__name__)
app.config['MONGO_URI'] = "my-uri-is-here"
mongo = PyMongo(app)

@app.route('/')
def index():
    return '''
        <form method="post" action="/create" enctype="multipart/form-data">
            <input type="text" name="username">
            <input type="file" name="profile_image">
            <input type="submit">
        </form>
    '''

@app.route('/create', methods=['POST'])
def create():
    if 'profile_image' in request.files:
        profile_image = request.files['profile_image']
        mongo.save_file(profile_image.filename, profile_image)
        mongo.db.imageusers.insert_one({'username' : request.form.get('username'), 'profile_image_filename' : profile_image.filename})
        return 'Done!'

@app.route('/file/<filename>')
def file(filename):
    return mongo.send_file(filename)

Like I said, the /create route works fine, but when I go to /file/cat.jpeg, I get this error:

Traceback (most recent call last):
  File "/mnt/b/Documents/Miguel/UT/Advanced_Programming_Tools/mongo_images_test_flask/wslenv/lib/python3.8/site-packages/flask/app.py", line 2091, in __call__
    return self.wsgi_app(environ, start_response)
  File "/mnt/b/Documents/Miguel/UT/Advanced_Programming_Tools/mongo_images_test_flask/wslenv/lib/python3.8/site-packages/flask/app.py", line 2076, in wsgi_app
    response = self.handle_exception(e)
  File "/mnt/b/Documents/Miguel/UT/Advanced_Programming_Tools/mongo_images_test_flask/wslenv/lib/python3.8/site-packages/flask/app.py", line 2073, in wsgi_app
    response = self.full_dispatch_request()
  File "/mnt/b/Documents/Miguel/UT/Advanced_Programming_Tools/mongo_images_test_flask/wslenv/lib/python3.8/site-packages/flask/app.py", line 1518, in full_dispatch_request    
    rv = self.handle_user_exception(e)
  File "/mnt/b/Documents/Miguel/UT/Advanced_Programming_Tools/mongo_images_test_flask/wslenv/lib/python3.8/site-packages/flask/app.py", line 1516, in full_dispatch_request    
    rv = self.dispatch_request()
  File "/mnt/b/Documents/Miguel/UT/Advanced_Programming_Tools/mongo_images_test_flask/wslenv/lib/python3.8/site-packages/flask/app.py", line 1502, in dispatch_request
    return self.ensure_sync(self.view_functions[rule.endpoint])(**req.view_args)
  File "/mnt/b/Documents/Miguel/UT/Advanced_Programming_Tools/mongo_images_test_flask/example.py", line 29, in file
    return mongo.send_file(filename)
  File "/mnt/b/Documents/Miguel/UT/Advanced_Programming_Tools/mongo_images_test_flask/wslenv/lib/python3.8/site-packages/flask_pymongo/__init__.py", line 206, in send_file
    response.set_etag(fileobj.md5)
  File "/mnt/b/Documents/Miguel/UT/Advanced_Programming_Tools/mongo_images_test_flask/wslenv/lib/python3.8/site-packages/werkzeug/sansio/response.py", line 502, in set_etag
    self.headers["ETag"] = quote_etag(etag, weak)
  File "/mnt/b/Documents/Miguel/UT/Advanced_Programming_Tools/mongo_images_test_flask/wslenv/lib/python3.8/site-packages/werkzeug/http.py", line 855, in quote_etag
    if '"' in etag:
TypeError: argument of type 'NoneType' is not iterable