Nuxt SSR support

Gridstack version 7
Nuxt with SSR

Steps to reproduce
1. Create a nuxt app
2. Add a gridstack.init
3. See the error
<img width="2454" alt="image" src="https://user-images.githubusercontent.com/3810177/195294349-b554ae4c-9a01-4dd6-822f-a2b8f27d090e.png">

## Expected behavior
No errors

## Actual behavior
Errors
