examples(with-sockets): fix cannot read property 'app' of undefined on nuxt build

[reskume]

The provided example works flawlessly in dev mode but when "nuxt build" is run, the build will fail with an error "Cannot read property 'app' of undefined" since the renderer is not available yet. By using the 'render:before' hook to assure that the renderer is available, it works as expected. This may not be the best solution but worked for me.

Types of changes

• Bug fix (a non-breaking change which fixes an issue)
• New feature (a non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Description

Checklist:

• My change requires a change to the documentation.
• I have updated the documentation accordingly. (PR: #)
• I have added tests to cover my changes (if not applicable, please state why)
• All new and existing tests are passing.

[pi0]

Thanks!