[EuiIcon] Early setState yields a console error

[Phizzard]

Summary

Fixes #4783

Using <EuiIcon /> with React.StrictMode would yield the following react warning Warning: Can't call setState on a component that is not yet mounted. This is a no-op, but it might indicate a bug in your application. Instead, assign to 'this.state' directly or define a 'state = {};' class property with the desired state in the EuiIcon component.

This would happen because the loadIconComponent() function calls this.setState() and is used in the constructor.

Moving the the loadIconComponent() and logic around it in the constructor to componentDidMount() resolves this warning.

Checklist

• Check against all themes for compatibility in both light and dark modes
• Checked in mobile
• Checked in Chrome, Safari, Edge, and Firefox
  - [ ] Props have proper autodocs and playground toggles
  - [ ] Added documentation
• Checked Code Sandbox works for the any docs examples
  - [ ] Added or updated jest tests
• Checked for breaking changes and labeled appropriately
• Checked for accessibility including keyboard-only and screenreader modes
• A changelog entry exists and is marked appropriately

[kibanamachine]

Since this is a community submitted pull request, a Jenkins build has not been kicked off automatically. Can an Elastic organization member please verify the contents of this patch and then kick off a build manually?

[thompsongl]

Thanks, @Phizzard!

[thompsongl]

This has already been called in the constructor. Should be able to just use the icon value in state

[Phizzard]

Gotcha! I'll make this change

[thompsongl]

Be sure to merge/rebase master and move this to the correct location; we've had a release(s) and this is now outdated.

[Phizzard]

@thompsongl Changes should be good for re-review :)

[thompsongl]

Thanks, @Phizzard

Using the reproduction steps mentioned in #4783 (comment)
I am still getting a "Can't perform a React state update on an unmounted component" warning.
There might be more to this than just moving the initial setState call, but I haven't investigated further.

[Phizzard]

@thompsongl Ah, the way I was reproducing was just wrapping any example of EuiIcon in React.StrictMode. Moving that logic into didMount resolves that, but I can take a little investigation on what causes the warning with the reproduction steps mentioned!

[siminture]

Why this issue is still not fixed?

[chandlerprall]

Just doing some cleanups, @Phizzard are you still interested and available to work through this issue?