Prevent setState after unmount

[spenserblack]

Hello 👋

When running emoj with no arguments, then typing any string of characters, followed by pressing esc, I noticed that I was getting

Warning: Can't perform a React state update on an unmounted component. This is a no-op, but it indicates a memory leak in your application. To fix, cancel all subscriptions and asynchronous tasks in the componentWillUnmount method.
    in Emoj (created by Context.Consumer)
    in Unknown
    in App

I narrowed this down to fetchEmojis attempting to set the state after the component had unmounted.

This PR prevents that warning by blocking fetchEmojis from attempting to set state after a user has input ESC.

I'm unfamiliar with using React components in CLI applications, so I apologize if these changes do not follow best practices.

[sindresorhus]

There must be a better way to resolve this than adding more state.

[sindresorhus]

// @vadimdemedes

[spenserblack]

There must be a better way to resolve this than adding more state.

Most likely 😆 . I originally put it in there in case you wanted to do something with an exiting state, but probably best to be left out after all. I just pushed up a different commit which doesn't set state. Instead it just uses this.exiting. I opted not to store the value in props, since it's a value that should always be false on instantiation.

But I feel like there's still a better solution somewhere 🤔 . Setting an exiting variable still feels a bit inelegant 😆 .

[vadimdemedes]

I think this should no longer be an issue after https://github.com/sindresorhus/emoj/pull/46 is merged.

[sindresorhus]

Fixed by https://github.com/sindresorhus/emoj/pull/46