CODE EXAMPLE FOR JAVASCRIPT

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