[BUG] Multiple issues in 4.0.0

[dogawaf]

Since 4.0.0 and the compatibility with TYPO3 12, multiple issues have been introduced, especially with the migration from Slots to Events.

Example here https://github.com/pixelant/pxa_social_feed/blob/master/Classes/Feed/Update/TwitterV2FeedUpdater.php#L43 where $this->eventDispatcher is null.

Also, some introduced Events class are incompleted and are unusable, like BeforeReturnTwitterQueryFieldsEvent which need to provide the feed's Configuration object to listeners in order to be useful.

I will provide a PR to fix those issues.

Furthermore, I suggest to refactor the whole DI thing:

• use constructor injection by default
• adjust the Services.yaml file
• fix tests

Because it's for 4.0.0, which is not yet available on TER, I think those breaking changes can be introduced.

What do you think?

[MattiasNilsson]

@dogawaf Great add a PR and we will check it out.