Improve handling of empty data

Just pushing a WIP - not sure I got all the tests.

I think after working with feeds again after a long time - we should be doing this.

I think skipping on empty should solve a lot of related issues.

I suspect we might also want to add follow up issues to relax some of the strictness / casting in other plugins - but I think for now we should make sure we are being consistent and easier to use with empty data.

Setting to needs work to cleanup test failures and coding standards

I was way too eager changing everything - a bit to revert / cleanup in the branch

Alright, reverted my over eager changes.

We would need additional tests to confirm this behaviour + document its intentions somewhere.

Are we in agreement @MegaChriz on this approach?

It might be a better idea for me to fix tests & commit the related issues first given I am sure on those issues, then come back to this parent issue to review implementing in the plugins I've changed here for consistency reasons. I'll try make the Friday feeds meetup to discuss.

I've update the MR with a bunch of tests, and tweaks to avoid calls to empty in situations where null is sufficient and safer.

If I get time, it could do with some tests around some of these plugins.

I'm also going to open a seperate issue as I was not sure if we should be removing the exception thrown in the Hash plugin.

Added some more tests for empty strings and cleaned up the comment on the null value tests.

I was unable to finish executing feeds-import because some data came in as NULL, triggering the exception and interrupting the batch import. I took the MR diff and applied it as a composer patch, it worked perfectly for me!

Thank you!

This worked well. Thanks for the patch.

Worth noting that a related issue was down to bogus whitespace at the end of the file, just after the final closing tag. The XML parser didn't seem to like that either.