TypeError: Cannot read property '_id' of undefined When I try to add a product

[HackIvan]

55 | }
56 |
57 | const variables = {

58 | writer: props.user.userData._id,
| ^ 59 | title: TitleValue,
60 | description: DescriptionValue,
61 | price: PriceValue,

I've created a mongo db account and I've created the dev.js file adding the credentials to in for accessing the database

[vishchi]

Yeah one thing, he mistakenly kept those <> around password and dbname inside the dev.js(config) file. You are supposed to remove those. It should look like:
module.exports = {
mongoURI:'mongodb+srv://bla_user:bla_pass@cluster0.skpel.mongodb.net/test?retryWrites=true&w=majority'
}
and if you don't already have a database created, please go and create in 'collections' section. In my case, it is named "test".