warnings when installing with yarn

[PutziSan]

This is a duplicate of #1207, but there is no further reaction and the problem is definitely not fixed yet. The very first impression of firebase when you install it with yarn is a real WOW-experience (wall-of-warning-experience):

And please, the solution is not "just use npm". If you want to leave it as peerDependency, okay, it's your package. But could you explain to us why you decide to do this? Maybe it's a very good point and we can learn something.

Please also see the comment at the corresponding yarn-issue: yarnpkg/yarn#5347 (comment)

[REQUIRED] Describe your environment

• Operating System version: win10, yarn-1.16.0
• Firebase SDK version: firebase@6.0.2
• Firebase Product: all

[REQUIRED] Describe the problem

When installing with yarn, warnings appear.

Steps to reproduce:

mkdir firebase-warning
cd firebase-warning
yarn add firebase

[google-oss-bot]

I couldn't figure out how to label this issue, so I've labeled it for a human to triage. Hang tight.

[Feiyang1]

Thank you for bringing this issue to our attention, again!

This is definitely not a good user experience and we should fix it given the fact that yarn is really popular nowadays. I made a PR to address it - #1807

As to why we keep @firebase/app-type as a peer dependency - it's because @firebase/app is a peer dependency and @firebase/app-type should be the same one that @firebase/app depends on.

It makes sense for @firebase/{component} (e.g. @firebase/firestore, @firebase/auth) to peer depend on @firebase/app, otherwise if you install @firebase/{component} individually and each of the component depends on a different version of @firebase/app, you will run into incompatible firebase instances and other weird issues caused by it.

[Feiyang1]

Closing this as 6.0.4 is out with the fix.