Warning when adding generateEtags: false

[emkayy]

When I add the line generateEtags: false,

to next.config.js
I get the warning:

warn  - Invalid next.config.js options detected: 
[
  {
    "instancePath": "/generateEtags",
    "schemaPath": "#/properties/generateEtags/isFunction",
    "keyword": "isFunction",
    "params": {},
    "message": "must pass \"isFunction\" keyword validation"
  }
]
See more info here: https://nextjs.org/docs/messages/invalid-next-config

I don't know what's wrong about this since it's just a boolean value and it's like that in the documentation.