app: console errors (Jan 2020)

[jorgeorpinel]

A couple lines printed a lot by the server are

[ event ] client pings, but there's no entry for page: /doc
[ event ] client pings, but there's no entry for page: /_error

Not errors, but look strange. Especially "no entry for page: /doc". We have pages/doc.js

And a rendering warning when loading /doc/user-guide (first time) is

Warning: Failed prop type: The prop `language` is marked as required in `CodeBlock`, but its value is `null`.
    in CodeBlock
    in ReactMarkdown
    in article
...
    in styled.article
    in Markdown
...
    in Context.Provider
    in AppContainer

[jorgeorpinel]

We're also getting

Browserslist: caniuse-lite is outdated. Please run next command `yarn upgrade`

in the console at build-time now.

[shcheklein]

Closing - probably not relevant anymore. Anyways, it should be ongoing effort of fixing these errors?