Specify compatibility with govuk-frontend v5

[frankieroberto]

The plugin works with either v4 or v5 of govuk-frontend

[frankieroberto]

v5 of govuk-frontend is coming (and can be tested already using a prerelease). The plugin works with v5 already, so we can specify this to avoid these warnings:

npm ERR! code ERESOLVE
npm ERR! ERESOLVE could not resolve
npm ERR! 
npm ERR! While resolving: @x-govuk/[email protected]
npm ERR! Found: [email protected]
npm ERR! node_modules/govuk-frontend
npm ERR!   govuk-frontend@"github:alphagov/govuk-frontend#5b2bfde4f" from the root project
npm ERR! 
npm ERR! Could not resolve dependency:
npm ERR! peer govuk-frontend@"^4.1.0" from @x-govuk/[email protected]
npm ERR! node_modules/@x-govuk/govuk-prototype-components
npm ERR!   @x-govuk/govuk-prototype-components@"^2.0.3" from the root project
npm ERR! 
npm ERR! Conflicting peer dependency: [email protected]
npm ERR! node_modules/govuk-frontend
npm ERR!   peer govuk-frontend@"^4.1.0" from @x-govuk/[email protected]
npm ERR!   node_modules/@x-govuk/govuk-prototype-components
npm ERR!     @x-govuk/govuk-prototype-components@"^2.0.3" from the root project
npm ERR! 
npm ERR! Fix the upstream dependency conflict, or retry
npm ERR! this command with --force or --legacy-peer-deps
npm ERR! to accept an incorrect (and potentially broken) dependency resolution.

Alternatively - we could remove the dependency on govuk-frontend entirely, as we already depend on govuk-prototype-kit which itself depends on govuk-frontend?

cc @paulrobertlloyd @colinrotherham

(I'm a little bit out of my depth on this stuff)

[colinrotherham]

Thinking about @paulrobertlloyd's comments in #110 a bit more:

Move govuk-frontend to peerDependencies. We need to indicate that this package only works with v4.1.0 or later (due to ESM changes in govuk-frontend and SCSS dependencies).

The warning above is doing exactly as designed, I think?

I'd wonder if you need optionalDependencies but do widen govuk-frontend if you need it at all?

-  "optionalDependencies": {
-    "govuk-prototype-kit": "^13.13.1"
-  },
  "peerDependencies": {
-   "govuk-frontend": "^4.1.0"
+   "govuk-frontend": "^4.1.0 || ^5.0.0"
  },

I'd assume you can temporarily use "^4.0.0 || ^5.0.0 || ^5.0.0-testing" to test out the preview

[colinrotherham]

Watch out for other plugins requesting govuk-frontend via govuk-prototype-kit too

For example, running npm ls govuk-frontend in govuk-prototype-filters outputs:

└─┬ [email protected]
  └── [email protected]

[paulrobertlloyd]

Brainy hurty. Meanwhile: alphagov/govuk-frontend#4353