Fixed an issue with throwing an exception when HotTable component state is changed

[wszymanski]

Context

It seems that render done by Formulas plugin while component state is changed causes an error. When we have an application which shows two or HotTable each of them resets some internal properties (done by methods attached to ref attributes - see below).

handsontable/wrappers/react/src/hotTable.tsx

Line 523 in b4d9477

<div ref={this.setHotElementRef.bind(this)} {...containerProps}>

handsontable/wrappers/react/src/hotTable.tsx

Line 526 in b4d9477

<RenderersPortalManager ref={this.setRenderersPortalManagerRef.bind(this)} />

Any extra call of Hansontable's render method cause access to nulled values. Thus, an exception in thrown. This PR stops renderers actions from execution while component isn't mounted.

How has this been tested?

Wrote application which use two instances of HotTable component

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature or improvement (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Additional language file or change to the existing one (translations)

Related issue(s):

1. https://github.com/handsontable/dev-handsontable/issues/1334

Affected project(s):

• handsontable
• @handsontable/angular
• @handsontable/react
• @handsontable/vue
• @handsontable/vue3

Checklist:

• I have reviewed the guidelines about Contributing to Handsontable and I confirm that my code follows the code style of this project.
• My change requires a change to the documentation.

[github-actions]

Launch the local version of documentation by running:

npm run docs:review 74aa42e0c32351fcc4cf24e790c8bfdbf96031a3

[wszymanski]

There is one not passing tests which can't be reproduced by me on local environment.