Google Cloud Function: Dependency not found - vue.js

Question

I am developing a project on Nuxt that I am deploying as a Google Cloud Function. (I Chose this as I am using a Cloud Firestore for my data storage)
It all works very nicely so far (Except the cold start time is persistently high - about 6 seconds but I think that is a separate matter). However, I keep getting this WARN in the logs on my Cloud Function:
textPayload: " WARN The dependency eslint not found. Please run yarn add eslint --dev or npm install eslint --save-dev"
There is nothing in the error to suggest where it is requiring eslint or why. This does not happen when I run my code or deploy locally.
My package.json looks like this:
{
"name": "functions",
"description": "Cloud Functions for Firebase",
"scripts": {
"serve": "firebase serve --only functions",
"shell": "firebase functions:shell",
"start": "nuxt start",
"deploy": "firebase deploy --only functions",
"logs": "firebase functions:log"
},
"engines": {
"node": "10"
},
"dependencies": {
"#nuxtjs/axios": "^5.9.7",
"#nuxtjs/eslint-config": "^2.0.0",
"#nuxtjs/eslint-module": "^1.1.0",
"#nuxtjs/vuetify": "^1.10.3",
"cookieparser": "^0.1.0",
"firebase": "^7.13.2",
"firebase-admin": "^8.6.0",
"firebase-functions": "^3.3.0",
"js-cookie": "^2.2.1",
"jwt-decode": "^2.2.0",
"nuxt": "^2.12.2",
"nuxt-client-init-module": "^0.1.8",
"nuxt-start": "^2.11.0",
"vuetify": "^1.0.0",
"selectiveSSR": "file:./local-modules/selective-ssr",
"shortid": "^2.2.15",
"sortablejs": "^1.10.2",
"vue-moment": "^4.1.0",
"vue-uuid": "^1.1.1",
"vuex-persistedstate": "^3.0.1"
},
"devDependencies": {},
"private": true
}
The Warning suggests it is looking for a dev-dependency. Surely I don't need these in my package.json? (Even if I add it in I still see the warning). There are references to the eslint package in my package-lock.json (which makes sense as I guess the nuxtjs/eslint packages in my package.json need it) but:
The link to the gzipped eslint NPM in package-lock.json works OK when I access it in my browser
Should Google not be using its Package Cache anyway to speed up the cold start? Is the issue that the specific version of eslint package-lock.json refers to is not available in Google's local package cache?
And yes I have tried adding eslint to my dependencies and devDependencies and it makes no difference.