Functions declared in data are cleared when fetch is present

[becrespi]

Versions

• nuxt: 2.12.2

Reproduction

https://codesandbox.io/s/distracted-sky-tdi6b

Additional Details

Steps to reproduce

Declare a function as variable inside data in a page

What is Expected?

Access to that variable and use it

What is actually happening?

The variable is empty if I use fetch hook of nuxt. The problem occurs only in ssr mode, if go to the page with the navigator all is working as expected.