Remote .js file on the disk does not get rendered as a Schema in Swagger UI

My .yml code is the following:

/user: post: tags: - "user" summary: "Register User" requestBody: description: Req.body containing firstname, lastname, eMail, street, salutation, phonenumber, telephone, city, PLZ, password, lastlogggedin, loginattempts, lockuntil required: true content: application/json: schema: $ref: "../../models/user.js#/userSchema"

The problem is that the Schema does not get rendered, even though the path is correct. An error stating that the basePath is undefined gets thrown out.