Migration guide for 4.0

[SoundBot]

After upgrading to 4.0 I'm getting a lot of errors about my store.getState() usage: You may not call store.getState() while the reducer is executing. It was working without any issues in 3.7.2
I don't see any migration guide. Please advise.

[markerikson]

There really shouldn't be any migration guide, because the changes were primarily around TypeScript typings.

Can you provide a project that reproduces the issue? Just saying that the error is happening doesn't tell us what's going on.

[SoundBot]

@markerikson I'm calling store.getState() inside one of my actions. I strongly suspect that this commit #1569 is causing this issue.

[markerikson]

As I said: please show the code that is involved here, preferably the entire application if possible.

[timdorr]

Please see #1568. If you've already started the dispatch process and are calling another action, it sounds like you have an impure reducer, which is an anti-pattern in Redux.