[vue-function-api] "onMounted" get called outside of "setup()"

[Timkor]

I am trying to create a hook:

import { value, computed, watch, onMounted } from 'vue-function-api';

export function useIntersectionObserver() {

    let intersectionObserver;

    const entry = value({});

    const callback = (entries) => {
        if (entries.length > 0) {
            entry.value = entries[entries.length - 1];
        }
    };

    onMounted(() => {
        intersectionObserver = new IntersectionObserver(callback);
        ...
    });

    onUnmounted(() => {
        intersectionObserver.disconnect();
    });

    return {
        isIntersecting: computed(() => entry.isIntersecting)
    };
}

And use that in some component:

  import { value, computed, watch, onMounted } from 'vue-function-api';
  import useIntersectionObserver from '...';

  export default {
    setup() {

      useIntersectionObserver();
    }
  }

Yet, I get the error:

[vue-function-api] "onMounted" get called outside of "setup()" 

Why is that, and how can I prevent this?

[liximomo]

Sorry. Can't reproduce it. https://codepen.io/liximomo/pen/KjXXBY?editors=1011

[Timkor]

I use it at SSR (nuxt.js). Might be the cause? I'll provide a reproduction link tomorrow.