In ZTypedMapTest.php, there are several constructor calls like this:
new ZTypedList( ZTypedPair::buildType( 'Z6', 'Z40' ), ...
I believe it should be like this:
$elementType = ZTypedPair::buildType( 'Z6', 'Z40' ); new ZTypedList(ZTypedList::buildType( $elementType ), ...
Note: recently the first type of construct above caused a bug; changing it to the 2nd construct fixed the bug. See comments in https://gerrit.wikimedia.org/r/c/mediawiki/extensions/WikiLambda/+/815334