Fix non-list dynamic content in Trans component

[nicegamer7]

Hi! This PR closes #1658.

Changes

• Always return children as an array from getChildren (for isI18nDynamicList)
  • This is the bugfix
• Reduce false positives when checking for nodes needing handling with empty children
  • This is just something I noticed while working
• Remove React warnings in Trans component by removing i18nIsDynamicList prop while rendering
  • Again, this is just something I noticed and thought to fix while I was at it

Checklist

• only relevant code is changed (make a diff before you submit the PR)
• run tests yarn test
• tests are included
• commit message and code follows the Developer's Certification of Origin

[coveralls]

coverage: 96.167% (+0.2%) from 95.98% when pulling 5e34bdd on nicegamer7:hotfix/dynamic-content into f8ea7d8 on i18next:master.

[jamuhl]

What is the use case of having i18nIsDynamicList in combination with a non-list?

You give the sample:

<Trans>
  Hi there,{' '}
  <React.Fragment i18nIsDynamicList>
    {someDynamicVar}
  </React.Fragment>
</Trans>

which has nothing todo with the usage of i18nIsDynamicList

that flag is only used for creating the string for saveMissing feature and only for the case where content is like: https://react.i18next.com/latest/trans-component#using-with-lists-v10.5.0

[nicegamer7]

In our project we're using key fallback for all translations, so the key for <Trans>Hi</Trans> would be "Hi". This worked well for 99% of our project, but in a couple places, we had dynamic variables being used, and these weren't being extracted correctly by i18next-parser (rather than extracting as <3></3> for example, it extracted as {someDynamicVar}). This caused the translations to not get matched properly to their respective Trans elements, so I thought this was the expected behaviour since it worked with fine with i18nIsDynamicList (after this bug fix, and another to i18next-parser).

It seems extracting JSX expressions is broken in i18next-parser, so I'll get that fixed in another PR. Regardless though, there is still a valid use for this PR which I came across in another file yesterday:

<Trans>
  <React.Fragment isI18nDynamicList>
    {list.length === 1 ? list[0] : list.map((x) => <div> ... </div>)}
  </React.Fragment>
</Trans>

We have a couple different pieces of code that are similar to the above in our project, where we want to display the list differently depending on whether it has 1 element, or multiple. We could split it into a ternary with two Trans elements, but this reduces duplicate code.

[adrai]

@nicegamer7 shouldn't that warning be gone?

// cc: @pedrodurek

[adrai]

btw: included in v13.1.0

[nicegamer7]

@adrai I wasn't able to remove the warning from React.Fragment, since it has its own validation that happens before rendering occurs. But the warning is removed for all HTML elements.