fails:Enumerator::Lazy#collect_concat sets nil to size
fails:Enumerator::Lazy#collect_concat when the returned lazy enumerator is evaluated by Enumerable#first flattens elements when the given block returned an array or responding to .each and .force
fails:Enumerator::Lazy#collect_concat on a nested Lazy sets nil to size
fails:Enumerator::Lazy#collect_concat on a nested Lazy when the returned lazy enumerator is evaluated by Enumerable#first flattens elements when the given block returned an array or responding to .each and .force
