This happened because I had followed the guidance at https://nuxt.com/docs/4.x/guide/concepts/typescript#type-checking and installed vue-tsc and enabled typescript type-checking at run/build time. I don't know why it wasn't an issue previously but what I needed to do was run npm install @types/node --save-dev. (I did not need to add "types": [ "node" ] to the compilerOptions section of my tsconfig.json file.)