mongoparseerror: option usecreateindex is not supported
This happend because in mongoose version 6 and above don't require those
" { useNewUrlParser: true,
useUnifiedTopology: true,
useCreateIndex: true,
useFindAndModify: false,} "
so just delet it.
And if you still see "app crashed - waiting for file changes before starting..."
just save it one more time and it will work