method init_app of MongoEngine can't use config from __init__

[minghu6]

I create MongoEngine somewhere: db = MongoEngine(config=myconfig)
And init the app int the app.py(flask entrypoint) :

app = Flask(__name__)
db.init_app(app)  # import from above

It's wired that MongoEngine instance use None instead of myconfig as its config.

I strongly recommend to hold the config when __init__ and check self.config in init_app

flask-mongoengine/flask_mongoengine/__init__.py

Line 128 in a0b0cf8

if not config: