Cannot run with sound null safety because dependencies don't support null safety

I have followed ["Enabling null safety" on `dart.dev`][1] and also [**migrated**][2] my whole Flutter application to null safety.

Now, I am trying to run it using `flutter run`. However, it will not start because of the following error:

```lang-none
Error: Cannot run with sound null safety, because the following dependencies
don't support null safety:

- package:cloud_firestore_web
- package:firebase_core_web
- package:shared_preferences
- package:url_launcher_web
- package:firebase_auth
- package:http
- package:provider
...

For solutions, see

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Failed to compile application.
```

The guide at the URL says that I should ["wait for dependencies to migrate before you migrate your package"][3], but I want to use [non-nullable by default][4] (NNBD) now.

How can I do that?

[1]:

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[2]:

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[3]:

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[4]:

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