Add linter rule to enforce proper type imports about lodestar HOT 3 OPEN

consistent-type-imports/ and consistent-type-exports/ rules do address this. Their usage is detailed on elsint blog.

Applying them on lodestar code base produces the following result:

✖ 3176 problems (3114 errors, 62 warnings)
  3104 errors and 0 warnings potentially fixable with the `--fix` option.

Most of those errors can be fixed by eslint. Evenso the number of files impacted is huge, it might still be woth doing for the following reasons:

• do not depend on import side-effects for proper behavior
• allow tree-shaker to remove unneeded code (and reduce bundle sizes)

from lodestar.

I'm in favor of adding these linter rules 👍

• Also linking this other issue, #6011, since a nice endgame would be to have consistent rules across all our maintained repos.

from lodestar.

it might still be woth doing for the following reasons:

Looking at some examples in our code

Note that we already have import/no-extraneous-dependencies which prevents you from using fastify as a value in the api package as it is only a dev dependency.

I am not fully convinced that type imports are that useful in most cases, do we have an example in Lodestar were this makes a difference? As far as I can see the change from normal to type imports in #6384 does not matter

Not against adding these rules but we should have at least one specific case were a lint rule would have saved us before adding it.

from lodestar.