reuse $row->getSubtable() as much as possible instead of callng Manager::getInstance()->getTable which can throw exception refs #3414
Tweak exception message
adding @group tag
Remove code that we're not sure why it's here
Make sure not to fail in getSubtable()
this code is  actually tested  for in DataTableTest::test_serializeFails_onSubTableNotFound
Fix refactor fail
Merge pull request #6836 from piwik/3414

refactor to prevent API error "This report has been reprocessed since your last click"