gatsby-plugin-theme-ui - Add compatibility for Gatsby 3

[moyarich]

Gatsby is now at version 3, this package is using Gatsby 2 as a peerDependency.

When can we expect a version bump for the gatsby-plugin-theme-ui to its next major version ?

[lachlanjc]

Great idea! We'd love a PR. Is it working right now but with a warning, or are there changes to the code we need?

[moyarich]

I don't know enough about the plugin to test all functionality myself but here is how to trigger the issue.

recreate dependency issues:

Could not resolve react peer dependency issue :
react@^16.11.0 from [email protected]

mkdir testapp && cd testapp && npm init -y
npm install gatsby react react-dom
npm install theme-ui

Could not resolve gatsby peer dependency issue :
gatsby@^2.13.1 from [email protected]

npm install gatsby-plugin-theme-ui 

[lachlanjc]

Ah yeah. We’ve got issue #1563 for tracking this fix!