[BUG] Solr response 400 ("Bad request") due to illegal characters?

[kitzberger]

Describe the bug

A 400 ("Bad request") response from solr doesn't seem to be handled as an error but leads to the indexing queue being stuck at where it's at.

To Reproduce

We've got the following config for tx_news_domain_model_news records:

plugin.tx_solr.index.queue.tx_news_domain_model_news.fields {
      ....
      teaser = teaser

      content = SOLR_CONTENT
      content {
        cObject = COA
        cObject {
          10 = TEXT
          10 {
            field = bodytext
            noTrimWrap = || |
          }

          20 = SOLR_RELATION
          20 {
            localField = content_elements
            foreignLabelField = bodytext
            singleValueGlue = | |
          }
        }
      }
      ...
}

The error can only be seen after adding an else into EXT:solr/Classes/IndexQueue/Index.php->indexItem():

            if ($response->getHttpStatus() == 200) {
                $itemIndexed = true;
            } else {
                var_dump($item);
                var_dump($itemDocument);
                var_dump($response);
                throw new Exception('Solr Response: ' . $response->getHttpStatusMessage(), 1637318787);
            }

Here's the error message:

Error adding field 'content'='lorem ipsum' msg=Multiple values encountered for non multiValued copy field teaser: lorem ipsum"

I can only assume that it's gotta be related to that part of general_schema_fields.xml:

	<copyField source="content" dest="teaser" maxChars="300" />

Expected behavior

The indexing failure should be properly logged as an error and the item thus skipped on subsequent runs.

Used versions:

• TYPO3 Version: 9 and 10
• EXT:solr Version: 11.0.x
• Used Apache Solr Version: 8.2.0
• PHP Version: 7.4.0